Not really a prank, but I've seen it done to great effect...

There's always one person farrrr drunker than everyone else.. tell them it's 'fuck a munter' night, and everyone has to go off and do whatever they can with as many as possible.

This is of course total lies, and he's the only one doing it. Everyone then stands on the balcony and watches with amusement. It's sort of like a strobe version of 'Where's Wally'...