After the "I DERIVE YOU" math joke (posted somewhere in the stickys) Here is one having a similar punchline, but, in my son's opinion, with a MUCH better joke: A constant function and an exponential function are walking down the street and they see a partial derivative. "Go over and talk to her" says the exponential function. "I cant, she'll differentiate me and I'll disappear!" says the constant function. The exponential function says "Okay, I will then. I'm e to the x!". So he goes over and says "Hi, I'm e to the x!" The partial derivative says "Hi! I'm d/dy" Yeah! (Also celebrating said son's graduation Master's Math at Exeter, so I am going to be telling all and sundry lame math jokes for about a week!) Yeah! Yeah!