Bouncer

noun

1. A member of security personnel employed by bars, nightclubs, etc to maintain order and deal with patrons who cause trouble.
2. A short-pitched ball that bounces up towards, or above the height of the batsman’s head.
3. An account or server (as with IRC and FTP) that invisibly redirects requests to another, used for anonymity or vanity.
4. One who bounces; a large, heavy person who makes much noise in moving.
5. A boaster; a bully.