Up Down Up Down Circle Circle Rinse

I was stopped at a red light this morning on my way into work. I noticed that in the car ahead of me, the dude's head suddenly started bobbing side to side really quickly. This wasn't a rockin-to-the-beat type motion (unless the beat was sideways). Was he having a seizure? I watch a lot of House and Grey's Anatomy so I figured I could probably save him.

Upon closer inspection, I discovered he was brushing his teeth. Well, that's all fine and good. But one question remains. What was he going to do with all that spit?