1. One of the ultimate disses indicating that the other person is some sort of degenerate.
2. However, it's meaning does not always have to mean degenerate - being a 'beitman' can also indicate that one is an extremely excessive video gamer.
3. Furthermore, a 'beitman' is one with a bowl cut.
'Beitman' is frequently capitalized, even in the middle of a sentence, though the street does not have any definitive rule on this.
1. Why are you humping that man? You are being such a beitman!
2. Dude, it's been three straight days now. You've been logged into counterstrike for over seventy hours. Go outside and stop being such a beitman.
3. Dude, what the fuck is up with your hair! Did they cut you with a bowl on your head for $1.75? That has to be the most beitman haircut I have ever seen...EVER!