One who repeatedly beats his rod (in a sporaticly random motion, similar to banging a kettle drum) against the vaginal mound. The purpose to either further stimulate the clit/penis or to maintain a solid erection. In some cases "bush whacking" is used to intensify orgasm after "pulling out" instead of the more commonly used hand jerking motion.
"Judy finished cumming just as Harold pulled his rod out, finishing the fuck with a vigorous bout of bush whacking, Harold quickly filled Judys navel with a stout squirt of man juice."
"That ol' Harold is one damn fine Bush Whacker"