Joining the Other side after you got treated like crap by yours.
I'm being treated like crap by my Artistic"friends." Screw them, I'm going to pull a Benedict Arnold and join the Jocks.
Someone who betrays everything they stand for seemingly out of the blue. Generally used in a political context.
Originated from the real Benedict Arnold, an American general in the Revolutionary War who famously betrayed America.
Dude 1: did you hear about biden changing his opinion about gay marriage
Dude 2: that was decades ago faggot
Dude 1: He's still a dirty benedict arnold.