A teacher or boss that is very strict about people getting in EXACTLY on time, almost always refuses to hand out bathroom passes, doesn't give you any real length of time for Lunch, and delights in writing you detentions or docking your pay for such infractions (just because he can). Refer to asshole or The Man for further information.
Man 1: God, Mr. Smith wouldn't let me go out for lunch AGAIN! He sucks!
Man 2: Yeah, Smith's an asshole! He's such a Door Nazi!
Man 1: You said it, dude!