A fantastic story from the US... more like this, please, yanks...
Mrs. Bergstrum the biology teacher clearly checked the wrong box when ordering dissectable fetal pigs from hog-bit providers Edmund Scientific.
What showed up instead was a reinforced drum of full-sized adult pig heads swimming in their own facial sweat. Making the best of her mistake, an attempt was made to dissect these in class, but this failed miserably as no one could get through the skull.
Sensing potential, someone slipped accidentally on purpose, a pig head ended up on the floor, a head was thrown, a girl screamed, and things went from bad to worse.
Soon enough, the unused heads began to disappear from their storage cabinet and show up in girls' lockers, the ball bin at the gym, staring up sadly out of the toilet bowl, etc.
For a few days, these heads were everywhere.
Interest waned when the fruit flies arrived.
Our GCSE Science teacher brought a set of pig's lungs to class, around which we all gathered to watch as she demonstrated their function and dissected them for us. As part of the demonstration, she stuck a tube into the windpipe, and asked Chris Belton to blow into the tube so we could see the lungs inflate. Chris obliged - only for someone to bring their fist down on top of the inflated lungs, shooting air and mucus from the lungs back up the tube and into Belton's mouth.
A name for the admitted rare phenomenon of a child with one webbed foot. The success of the insult really lies in the protracted nature of the linked insults, e.g. 'Pass me that pencil, oh you can't, pigeons don't have hands'.
Like sardines, yet more violent. Still catering to the newly evolved homoeroticism of school kids. Basically, someone falls over on the hard gravel floor of the playground, and everyone else jumps on them. Pile-ons were regularly arranged for various break times as well, but few people were daring enough to be the first. Often led to serious injuries.
All good friendships must face tests. My friendship with Pilky - a truly lovely chap - faced such a trial when I got him to place his foot over a rusty nail sticking out of a fence. Then, I stamped on his foot.
It is a testimony to the magnitude of my emotional givingness that we remained on good terms. That and the fact he promised not to grass me up.

There was a kid at primary school who claimed that he dreamt that he was eating a giant marshmallow and when he woke up, he had eaten his pillow.

I didn't know that this was a widely-known joke until recently when I was perusing a children's joke book.
The application of a ?nipple-gripple? and dead arm on the first day of the month to the chant of "Pinch-Punch, First of the Month!".
There was also the quasi-sophisticated retort "A punch and a kick for being so quick." This implied that the pinch-puncher didn?t even know the appropriate time for such tomfoolery, and had gone blustering in like an overexcited toddler.
The painless insertion of a pin under a layer of dead skin on the fingertip. Experts can manage ten pinfingers without accidentally popping one out. This leaves the pinfinger able to do little other than wave their hands at people and say "look look " to people they hope will be impressed. (Log)
In my third year of secondary school, we all went on "camp", and I went to the water sports one in Wales. Me and some other boys played a few games of the role playing game "Call of Cthulhu". While I was running one of these games, I made the mistake of saying that one of the beasts was "pink and blasphemous", within ear-shot of a school bully. I was hounded by cries of "pink and blasphemous" until the day I left that school, 5 years later.
Our teachers’ admin and staffroom corridor was, for some reason, painted a bright pink. Pupils would occasionally be dragged up for various disciplinary matters.

Fortunately, we were sophisticated and mature enough to appreciate and capitalise on the significant double-entendre opportunities. "Sir had to take her up the pink corridor for a punishment." Teachers could be asked if they were "going up the pink corridor for lunch".
If you tell anyone that you like Pink Floyd in year eight, you will be singled out as a bender.
Geography class year 8 1988, West London. A 12 year sick genius (I) believes that his C in recent report simply wasn't reward enough for his complete lack of effort, so hatches a plan so malignant that it just had to be great.
He and mates enter classroom. About 15 minutes in, with cumulus flying all around their very bored eardrums, yet not a pound of flesh in site, a solitary finger starts rhythmically tapping, ever, ever so slowly under the desktop.
You can't even hear it it is so quiet, but John, his friend, senses its vibration, and knows it is the Que for the devilish plan since (insert Blackadder type exaggerated description here using only the words Bielzebub, bottom, policeman, helmet, chewing gum, kazoo), and he added to the beat: da dada da da, da dada da da
Sajid wakes up and realises it is his moment and he joins in, louder and louder, teacher looks up over her glasses, which is easy because the top half of them seems to have been strangely and erroneously cut away, leaving only semi circles to look through, or more likely, over. Surely not practical.
Paul joins in, and then Michael and Jason; da dada da da, louder and louder, teacher "erm, whoever that is, will you, erm,,,,,,,,"
da dada da da, da dada da da,,,,,,,,,,,
"I am serious about this,,,,,stop 'right' now,,,," da dada da da, da dada da da Terry joins in, Matthew, Victor, Lillian, Kaye, Abbi, Dean,,,,
"will you all stop it right now, stop it, stop stop it, you little,,,,,stop it, the stratus lies above the erm, in certain wind erm, conditions, erm,,,,,,,,,,,,,"
da dada da da, da dada da da in chorus, right on que "we don't need no education, oi teacher! leave those kids alone" da dada da da."aaaaaaahhhhhhhhhhhhhhhhhhh" teacher flies from classroom in tears queuing outright yells of victory, high fives and celebrations all round.
Post script: festivities are short lived as teacher returns with deputy head Boon, a large 6'' 5' red headed bastard from the valleys. All participants instantly shit pants and think thrice about carrying out such pranks in the future.
The end (true story
An unfeasibly tall, largely silent, unassuming Asian girl who wore unnecessarily garish stripey leg-warmers. To our (suprisingly tolerant) six year old minds she seemed perfectly normal, little did we know the she was gaining reknown elsewhere.

This hidden notoriety only revealed itself more than 10 years later, at a party for a departing teacher, when parents and faculty members alike chose her as the subject for their fancy-dress costumes.
A game involving a number of people chasing each other around a car. All contestants are required to drink a can purchased from the local store. Then, chase each other around the car, attempting to trip the person in front of you. Continue until someone falls over. The unlucky individual would then be subjected to a hot, then almost immediately cold, drenching of piss. In cold weather, the urgency is increased, and so therefore is the risk of dirty tackles and wetting yourself.
A joystick-waggler game for the Atari ST, created by the Hot Spunk Crew.
Each level began with a sample from Jack Nicholson as The Joker, saying “Gentlemen – let’s broaden our minds”, after which you would immediately thrash your joystick from left to right. This action would animate one of a series of very short films, which included a bean-flicking incident and some hot three-way pixels.
Although obviously a humourous game, it was quite frustrating for people actually wanting to pleasure themselves, what with having your hands otherwise occupied. You could convince a friend to waggle the joystick for you; but if you’re that close you might as well just toss each other off anyway.
Additional features include colour cycling for those who want to watch green fingers slide into a deathly grey vagina.
The seemingly unlimited supply of empty camera film containers which we found in Mrs Bailey's classroom. These were urinated into, then left in a hidden spot for several days, so that they may mature. After this, the contents were emptied in a place where they would have most effect. A bald teacher walking underneath a window got a soggy head. In retrospect this was quite unacceptable behaviour.
If you smell very bad then it can be suggested that you shower by standing under a colander that your father is pissing into.
Toilet game perfected by Nick Edy, who would hurl a piss-drenched swaddling of tissue into an occupied cubicle, soaking anyone foolish enough to be ejecting brown at school.
Apparently, in Celtic mythology the goggle-eyed Pissgrabber lurked in the bowls of public toilets, attempting to insert a maths text book up the first arse that appeared. If the victim screamed the Pissgrabber returned to the Headmaster's office.
There were a number of factors that contributed to the terrible decision to piss in Steve's bed. It was the last day of a school trip to Austria. Two things had annoyed us throughout the week:

a) Steve
b) The utterly horrible food

So, to punish Steve and the hostel, all we had to do was piss in Steve's bed. When I say 'we', I mean 'I'. And so I found myself pissing onto a mattress in Austria.

In hindsight, it wasn't really worth it. My God, I can't believe I pissed onto somebody's bed.
Being at that age where penile exploration (and subsequent comparison) was particularly rife, three friends and myself thought it would be a cracking riot to share a communal piss in the "big kids" loos.
Giggling began as four streams joined togeteher in glorious Handelesque harmony, but it soon got too much to resist.
It started with a little flick, a little move to the side, then suddenly we were taken by the moment, spraying our urine on the toilet, walls, floors, and each other. We finished up, convulsing with laughter; the last boy making a show of it and spinning around in a 360 degree piss cycle.
We then opened the door to find our teacher standing there, fuming at our soaked trousers. Two boys started crying right there; I held strong though, until they broke me back in the office - the "getting your mum in" card was too damn effective.
Back when I were a lad, it was unthinkable to go to have a wee-wee in the urinals and NOT drop your trousers and pants to the floor. Thus, if you were to wander in at playtime, chances were you'd see a row of pink, hairless arses, staring at you like so many fat ladies' faces. I have often been tempted to attempt this at work, but fear that the hilarity of the occasion would be marred by the inevitable whisperings about my obvious perversion and weirdness if anyone caught me.
Where everyone stands along the urinal in the P.E. block. One shouts 'Pissy Circle' and does a nifty pirouette sending a looping strand of piss over his co-pissers.
A bomber jacket owned by Anthony Harrison had been stolen from the changing rooms during PE and was found at the back of the field slashed up and pissed on.
As if this wasn't funny enough in itself, he came in the next day wearing the SAME JACKET, that his mum had mended and washed.
This earnt him the nickname 'Trampony'.
One of the more dangerous forms of Kung Fu, especially in the hands of clumsy jumping juveniles whose only experience of martial arts is "backwards and fire for a roundhouse kick on Way of the Exploding Fist".
Battles last around 5 minutes, after which people will be bruised and breathless, unless someone has watched Van Damme's Bloodsport, in which case noses will generally be broken.