Math Humor

I heard a funny joke today in my Multi-Variable Calculus class today (at least I thought it was funny):

e^x is walking down the street when he meets 2x. He says to 2x, "Hey, didn't you used to be x²?" 2x replies, "Yes, but the differential operators are out today. Watch out!"

e^x keep walking, and just as 2x said, he runs into a differential operator. The operator says, "I'm gonna differentiate you to 0!". e^x laughs and says, "Just try! I'm e^x."

The differential operator laughs back and says, "Ah, but I'm ^d/_dy."