Chris is holding the flash above his head, and it's firing remotely. But since you can't see it, we'll just say that he's showing off his armpit hair.
Off-camera flash. It's supposed to provide better lighting, but I miscalculate and it doesn't work.
But the picture does lend itself to some cartoonish effects.
A miracle! Sadly, we couldn't get a picture of the front of this guy's shirt before the store asked us to stop taking photos. But you can still see that Peter's "Lubricant" t-shirt lives on!