You know when someone messes something up or does something stupid and all eyes are on them, so they try to defuse the tension by being funny (which usually backfires and makes people even more angry). I need a word to refer to that situation.
This is a tall order: none of the words here really conveys the idea that somebody is trying to defuse a tense situation -- only that somebody is making light of serious.
A word not yet appearing among the answers is flippant. The criticism above applies equally to this word, but at least it carries the idea that the audience is getting annoyed by the defuser.