irony
Opposite of something you would expect to happen, and/or something that completely contradicts what should happen. It also refers to dramatic irony, in which the audience is aware of information that the character isn't.
Not a lot of people actually know what irony is, so use http://tvtropes.org/pmwiki/pmwiki.php/Main/Irony for reference.
See also
- pool #3026 "You're the Last Person I Want to Hear That From" - this pool is used for more hypocritical behavior