To do something to intentionally piss one or more people off, for your own amusement.
Ex: Leeroy
Jenkins,
duh.
You can also use Leeroy for short.
Guy
1: "So yeah, I pissed a bunch of people off when I
lit some A&
F and Hollister clothes on fire, only to make a statement."
Guy 2: "I think they got the idea, Mr. Leeroy
Jenkins."
Guy 1: " Dude, watch this shit."
*Goes and does some shit to piss everyone off*
Guy 2: "What a retard."
Guy 3: "He's not a retard, he's.."
Guy 1: "LEEROOOOOOOOOOOOOOOOOOOY JENKINS!!"
Guy 2: "Goddamnit, Leeroy."