U.S. Olympic boxer Terrell Gausha is so disgusted over the George Zimmerman verdict ... he's vowing to never sport the red, white and blue again. Gausha -- who boxed in the 2012 London Summer Games -- started wearing the American flag on his boxing trunks after his Olympic run ... but tells TMZ he's done with that now in the wake of Zimmerman's acquittal in the killing of Trayvon Martin.