stimage
verb
To act in an unpleasant way while broadcasting your affiliation to a certain group, thereby damaging that group in the eyes of others.
I know not all Giants fans are loud, annoying drunks. But whenever I took Caltrain on a game day, the train was crowded with people wearing Giants merch - and the more they were wearing, the louder, more annoying, and more drunk they tended to be. While I’m sure I’ve met many more pleasant fans without realizing it, it’s hard not to have a negative reaction to even just a Giants cap after all the stimaging by every Giants fan I realized I was meeting.