Video after the jump.
Yikes. The logical explanation (and, frankly, the only explanation) is that he was trying to break his stick in frustration on the goal post and, well, you see what happened. This, of course, would be exhibit A as to why such a reaction is a very, very bad -- and careless -- idea.
Vokoun surrendered two goals on five shots and was replaced by backup Scott Clemmensen.
And, yes, something like this has happened before, as Tomas Surovy and Jaroslav Halak had a similar encounter at the World Championships back in May.