1 definition by Mr. Men

The only 'vitamin' on earth that will actually give you gains, hence the G.

i.e. steroids.
Bob: Jesus Christ, I've been getting no gainz lately. I'm thinking of hittin up some supplements or something.
Jim: Dude...there's no way to look like those guys from taking supps, they're all on vitamin G.
by Mr. Men December 6, 2016
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