Tell yer Mam
A great way of briefly scaring the shit out of somebody, without actually doing something they can be really angry about.

Your mate is standing on a ridge / riverbank / cliff. Push him hard toward the edge, and then yank him back in one fluid movement whilst shouting "Tell yer Mam I saved your life!"

We never actually did this on a cliff, but the minging pond in the school grounds was a popular choice.

Being harder than you, the hard kids would just push you in, shouting "Tell yer Mam I couldn't be bothered!"
That pond stunk.
written by an*nym*us*user, approved by Matt