Bumrush orginated when homeless peoples would come into a store and start loitering and casuing disturbances looking for places to sleep/eat/take shelter. These are stores such as super markets or retail stores. Store managers, became disgusted and tired of the homeless and degenerate roaming through their stores in search of warmth and possible indulgence of a twinkie or two. They went into the back storage room and usually took a broom and then went on a frenzying rush to rid their stores of bums. Thus the store went back to it's original status of a respectable and pleasant place to shop.
Gay guy #2:Yeah, he is soo hot. I'd love to bumrush him.
2) (v) To get beaten up by a large, angry group of people. Literally to get rushed by bums or lowlifes.