My current definition of irony is this statement, written by a student in a lecture summary that I had the privilege to mark:

Proof reading the paper by someone with string English skills is also a good way.

A close second is the news that one of the world's leading experts on bicycle and pedestrian safety was run over by a tour bus while crossing the street. I know, I know; we shouldn't laugh at these things. But they're funny, dammit.