Close cousin to 'shark in the buns', but with better results. When the unsuspecting victim (friend or stranger) bends over to pick something up. Shove your hand in their ass/crotch from behind, wiggle it around like a rabid animal and yell 'SQUIRREL IN THE FRUIT BASKET!'
Great at parties. Also works on girls.
'Hey i think you dropped a quarter.. SQUIRREL IN THE FRUIT BASKET!!!'