To get Steve Irwined is to be killed or greivously injured doing something you love in a really ironic way. Comes from the one time that Steve Irwin was killed by a manta ray while filming an underwater video.
Dude, did you hear about that stunt pilot? He was totally irwined! He was performing a Reverse-700-Pinwheel-Corkscrew when he flew into a migrating flock of Canadian Geese and exploded! What a way to go, eh?
It is said of the situation where a person has the bad luck to make contact with his testicles against an undefined surface or object, intentioned or not.
Given the nature of the word, it is more appropriate to design cases where the interaction is made with a moving object, for example, a ball.
Although it is extremely painful for the victim, it tends to be considerably funny to people who witness it.
Today in the baseball game the pitcher took a nutshot; the baseball hit him in the nuts.
Man, I just watched the funniest nutshot video ever.