Truly Terrible Jokes

Q: What is the volume of a pizza with radius z and height a?
A: pi z z a
I got this one off a university graduate. I was sat there stone faced when he told me it.
There is a maths party and all the functions are invited to it. Sine, cosine, log e^x and everybody else is there. During the party, cos notices that e^x is in the corner, by himself. Sp cosine walks up to e^x and asks him: "Why don't you come and integrate with everybody"? e^x replies, "I can't, I only integrate with myself".