When a man flirts with a woman for the sole purpose of asserting his masculinity. The man may be trying to impress his friends or simply stroke his ego. It is implied that the man is not actually interested in the woman or her reaction but is flirting with her for other reasons. One who plomps is plompous or a plomp-ass.
The hot guy down the hall got drunk one night and tried to flirt with me in front of his friends, it was so weird! He was totally plomping.