A phrase created by 2 University of Waterloo students in 2012.
The phrase refers to the often explosive bowel moments caused by the use of Mass Gainer supplements and used as a code word.

*Note these guys used 8-12 scoops of Mass Gainer a day, however they also trained very intensely and made significant gains. Drinking Mass Gainers without a proper workout regiment will mostly result in many MGMs and belly fat as well.

The movie studio whose movies and cartoons start with a mean lion roaring behind an elegant frame made out of film. MGM is known for their funny-ass cartoons like Tom and Jerry, and other characters like Droopy and Screwy Squirrel.

Hooking a battery up to a guys genitals could be considered MGM. Hugo Spadafora underwent MGM before being slowly beheaded. MGM remains popular in many countries outside the Western World as a way of making people tell them what you know.