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1.
An acronym for "Swear on my Great Grandmother's Grave".

Used in textspeak to prove you are telling the truth
Person 1: "I didn't post that on your wall."
Person 2: "You SO DID".
Person 1: "I didn't. SOMGGG"

or "Will pay it tonite. SOMGGG."
by Spacli October 04, 2011