A Northumbria University RAG team gesture as described bellow...
The idea of a crotch is quite simple- it merely involves the thrusting of the crotchal region into someone else while yelling "CROTCH!"
This may be performed at any time, place or occasion. Whether it is due to an innate desire to flirt or say hello, let someone feel your genetalia or merely an expression of goodwill, this craze is here to stay.
(Team 3 Leader creeps up behind team 3 member...creeping is optional but not necessary)