Somebody who is genuinely cool and quite chilled out.
Random Guy: Wow, he's cool!
Indie Kid: Yeah, he's a complete Jazz man.
A scummy child, teenager or young adult that lives in a council house. This name is apparent as most council houses have blue doors.
Blue Door Kids are often a nuisance and just make the place look untidy in their tracksuits.
Person 1: Wow! What a fucking chav!
Person 2: Yeah; complete Blue Door Kid.