to hurt yourself in a rather clumsy and outlandish way.
Often a serious injury or at least very painful looking.
A direct homage to the ridiculous ways actor John Ritter would prat fall throughout his career (most notably "Three's Company").
Dude, he rode his bike over the edge and rittered himself on a tree. It was awesome/terrible.
Don't jump like that man, you're going to ritter yourself on that railing.
Ha ha...did you see that? He totally rittered on that door!