For a guy with a history of violence against women ... a penchant for destruction ... and an explosive temper ... it's no surprise Chris Brown decided to be a Taliban fighter for Halloween.

Brown -- sporting a string of fake bullets across his chest -- rolled over to Greystone Manor last night ... to attend West Hollywood's biggest Hollywood party ... hosted by Rihanna.

Other famous in attendance ... Flo Rida, Paris Hilton and U.S. Olympic team superstar Lindsey Vonn ... but they all had better costumes.

Bonus Moronic Photo -- Before he hit the clubs, Chris and his buddies grabbed some fake guns and posed for a group shot. He posed the pic with the caption, "Ain't nobody F**king wit my clique!!!!"