where somone hits someone else in the area above the kneecap on the side of the left
leg with their own knee. why? because its bloody funny (only if it works)!! the consequense of this
will be the other person hopping on one
leg shouting swear words,while
u and ur m8s r laghing like
hell. also some advice: always give a grandad when the other person is noot expecting and make sure u r standing up when doing it. there are adaptions of the grandad like a 'running grandad', the 'spinny' and a 'flying grandad'.