Any comedian who used to be funny but now stars in exclusively terrible, unfunny movies. People who were never funny, such as Rob Schneider, are not technically classified as Enemies of Comedy.
Eddie Murphy is the #1 most wanted Enemy of Comedy for his long list of horrible movies following his awesome stand-up, time on early SNL, and first few good movies.
Blue comedy is a style of comedy that is off-color, risqué, indecent or profane, largely about sex. It often contains profanity and/or sexual imagery that may shock and offend some audience members.
Exactly the same style of comedy as "Stand-up comedy" except that you are sitting down while you are doing it.
(i.e. at a table, sitting at the bar, in a car, bus stop, office, etc.)
On a long cross-country road trip, I entertained Tina-Louise with hours of my sit down comedy.
I killed at the dinner table last night, it was pure sit-down comedy.