Noun, S.T.O.M.A. stands for Something Tribal on My Arm. In reference to a tattoo that took very little thought into getting and often lacks creativity and originality. The design of the tattoo is tribal artwork and usually in the form of a band.
This is when a complete jock or tool goes into a tattoo parlor and says "yeah...you know...i don't know what i want to get, i was thinking of getting something tribal on my arm...like a band going around my bicep or something...#117 looks cool, i'll take that" Hey man, how was the party? It was cool, a couple of meatheads showed up with Stoma tattoos on there arms and tried to pick a fight with us.