One of the classics... No idea in holy Sagan's hell who to attribute this to.
This is a favorite, and lots of people seem to be stealing it, and citing it as their own. I won't link to them so they don't get the exposure. The original author is located here.
I was stumbling about earlier, and came across a jacked post featuring this comic that was really funny. The poster was kind of a jerk, though, and did not link back, nor give credit. I figured these guys deserve a little promotion, and some evidence that not all content aggrigators are dicks. Check out their page: Saturday Morning Breakfast Cereal