How can I detonate my chicken?

The Witch Doctor "Hex" skill as a rune "Angry Chicken" where I can temporarily transform my corporeal form into that of a deadly exploding chicken. Fun, right?

However, I can't seem to figure out how to make my chicken explode. He just sort of stands there, or flaps about. Clicking on things doesn't seem to make anything interesting happen - not even a tentative peck. I thought maybe I exploded when the time ran out, but I just sort of poofed back into my normal form instead. The tooltips for the skill and rune are no help.

How can I unleash my mighty chicken wrath upon my enemies?

Your hotbar changes while self-hexed just like the Wizard's Archon transformation, though the skills aren't nearly as powerful (but they're still just as awesome).

Hit any of your skills (1-4) when in poultry form to explode.