Grundle is another word for chad: the region between the balls and the arse-hole; can be an erogenous zone for some.

Girl: I was fingering that part between his balls and his arse and there was shit there.
Everyone listening remained silent but later laughed among themselves:
'Eww! He had a shitty chad.'

When you measure your dick, you don't start at the arse-hole and include the chad; you risk getting shit on your measuring tape.

to tell someone to calm down and relax.

A protuberous underside. Particularly on an adorable animal.

The act of burrowing your nose into someones anus durring sexual playtime. A gluteal motor boat. Also known as a "Steam Boat Willy".

noun: The sweat off your balls.

the art of pulling down your pants and smashing your testicles and anus down on the head of a passed out human repeatedly.