This game is done by a large (8 or more will do) group of males. This works where one lucky guy (if you consider it lucky) gets blindfolded and spun around. After this, everyone, including the blindfolded guy, drops their pants and everyone stands in a circle around the blindfolded guy. Dazed and confused, the blindfolded guy (currently in the middle of the circle) walks backwards into one of the other guys' dicks. He then tries to guess who is... inside him. Hence the title of the game: Mystery Meat.
Kevin: Wanna get together with the guys and play some mystery meat tonight?
Rob: Nah, whenever I play I end up being the one blindfolded.