What do you say to a beautiful mathematician?

"I wish I were your first derivative, so I could lie tangent to your curves."

More humor: e∧x (that is, the mathematical constant "e" raised to the power of "x") went to party. He stood around morosely in a corner. The host came up to him and said "why don't you mix in with the other guests? Maybe that would cheer you up." He replied, "It's no use. If I integrate, I'll still be the same."

Commenters are urged to supply more calculus humor.