If you had to give up one thing for the rest of your life, Would it be brushing your hair or brushing your teeth?

I'd definitely go for dreadlocks. :)

I keep my hair short enough that it doesn't need brushing or combing.

There's no way I could go without brushing my teeth.

Pass the razor so I could shave my head. Not brushing one's teeth is just nasty and can cause all kinds of health problems.