somone who is from the southshore massachuset. These people are faggets and can go fuck themselves. the word is a mix of martians and people from mass(massins).
most niggers from duxbury are massins.
an abbreviation for the term masterbating
"dude i'll catch you later i'm massin"
can be used with a "t" replacing the "in"
i.e. "sorry man i have to go masst it"