there are actually 10 kinds of people in the world. those who understand binary, and those who don't. ba-dum pshh
Those Who Think There Are Two Kinds of People In The World and Those Who Don’t. Edit: Givers and takers.
Those who think there are only two types of people in the world, and those who don't. Edit: Whoa, beat me to it... I'll do another one. The skeptical and the gullible.