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 posted the pic with the caption, "Ain't nobody F**king wit my  clique!!!!"