I'm thinkin its a typo, and probably should have read MSOG, which stands for multiple shots on goal.

But I could be wrong

No, Stacy's probably right.  MSOG is multiple orgasms allowed.

Actually, I'm going with the MSOG typo.

a couple of others according to the Urban Dictionary.  Another one is it is an open mouthed kiss from a dragon... (not likely unless you are still intimate with your wife)
Go figure - link below to Urban Dictionary if you even care.