A McShlong is an extremely large penis, and certain indiviuals that wear tracksuits with goggles on them say this alot, because they think their penis is huge, but is in fact tiny.
Scally 1: Arrr mate, i cant cross my legs 'cause my McShlong gets in the way
Scally 2: I know how you feel mate.
A very very very big dick.
Hey man i just put my leg over my other leg and my mcshlong got squashed.
Holy fuck man, thats one hell of a McShlong! I want it inside me right now!
You got pummelled in the anus by a McShlong