Top Definition
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.
Example 1

man 1: Where are you going?

man 2: I have to take an MGM

Mass Gainer Moment- (aka MGM)

man 3: WTFs an MGM??

Ex 2.

man 1: Another MGM?

man 2: ya! its my 5th one today...the story of my life...
by adav December 14, 2012

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