Riemann jokes

Q. What's long, hard, and scary when you first see it?

A. Calculus homework.

My German girlfriend likes to rate our sex on a scale of 1-10.

Last night we tried anal, and she kept shouting “9!”

That's the best I've done so far.

4, 6, 8, and 9 have all been killed. 2, 3, 5, 7, and 11 are the prime suspects.

Roses are red, grass is greener. When I think of you, I play with my wiener.

What's black on top and white on the bottom?

rape.