chicken scratch
The use of the nail on the index finger of one hand to scratch the back of the other hand, repeatedly and continuously. The aim was to go past redness, rawness, and well into the open wound category leaving scabs for weeks and possible scarring. The really hard, and thus trendy people would rescratch partially healed scratches to ensure they were 'fresh'. The practice was banned in an assembly when a couple of kids got blood poisoning.
written by An*y Hol*, approved by Log

The competitive form of this game is known as 99s, where two people alternately scratch each others' hands in rounds of ten scratches.
written by Mi*hael *enn*ngs, approved by Log

At our school (after I left, fortunately for me), this was apparently done with paperclips, and it was so widespread that letters were sent to all parents to warn of the menace.
written by Je*f Sta*den, approved by Log

This got taken a stage further when some psychotics found that if you pulled a long piece of stiff wire hard and fast in a to and fro motion against a desk leg, friction would make the wire very hot. Very hot.
The fun was then to apply this home made branding iron to someone elses' flesh while it was still at max heat. The victim would have to show ultra-bottle by not flinching, screaming, or retching at the crematorium smells emerging from his cauterised arm.
There was interplay on the basis of how hot the victim thought the torturer could get the wire, how brutal he could be, and finally that it would then be time to reverse roles. So at first it could be quite experimental and gentle, no more than red marks or the odd blister. But then it got vicious.
It went wrong when the manky infected wounds were noticed, and a general inspection of the boys' limbs was held. The fact we all looked like deflated Michelin Men was noted, and we were all roundly bollocked.
written by Bo* Spa*he*ti, approved by Log

Sandpaper covers a wider area - perfect for the facial area. After repeated "sandpaperings" you'd look like you'd had a chemical peel.

Initially conceived as a method to pick on the lame and weak, this quickly became a badge of honour, so that after a week 95% of the male school children resembled burn victims.
written by sa*e m*n, approved by Phil

The process by which one girl (it was done mostly by girls at my school) would be repeatedly scratched by another girl on the forearm. This continued until blood flowed or the scratchie chickened out, due to a growing sense of pain, nausea and medical shock.
Devonshire girls... you gotta love 'em. Or they'll smash your fucking face in.
written by excluded pupil, approved by Log