Set tripping is actually the act of hanging with a set that isnt of your own. Like a 83rd street crip hanging with (and pulling out missions with) a shotgun crip.
"Sets" are refrences to street gangs. Set tripping is violent results from the confrontation of two rival gangs or gang members. Gang members identify eachother by tattoos, hand signs, and colors worn. Gang members or gangbangers rarley hesitate to attack another gang member who represents a rival gang.
"Ready to pop the clip in, ready to start (set) trippin'" - T.I.
We was in the club and this nigga' starts set tripping.
A certain 'hood, or block may be refered to as a "Set".
"What set you from, Nigga?"
Any gang violence or rivalry between "Sets" can be labeled as "Set Trippin".
"Homeboy from projects got killed by some set trippin ass niggas from the northside."
"Take that shit to the street, we aint set trippin up in here!"
To offend a group of peers through the means of acting a fool or just straight up buggin out or to make ones self look bad at inappropriate times and angering an opposing party.
Grandma: "happy birthday billy hope you enjoy your present"
billy: "socks again, oh man Grandma you be set trippin!"