Jokes that make you laugh cry or both

[angelfromanotherpin]

Despite xcvd's desperate attempts to convince us otherwise, there's no way this joke would work for a math professor, because everyone knows that just declaring your major as math causes a forcefield to form around your lower trunk, preventing any human flesh aside from your own from ever making contact with it. Forever.

I don't know if this one works as well in text form...

So, a college student majoring in math is working really hard on his final paper. His buddies are concerned that he's going to burn out, so they convince one of the girls in the dorm to seduce him for his own good. She shows up at his door, and says "Hey, how about some super sex?"

His response?

"Gee, thanks. I'll have the soup."

[Talisman]

Best pun I ever heard (although I realize that's like saying, "least painful punch in the nose I ever got"):

In LotR, you remember how Galadriel gave Gimli three strands of her hair? Do you know what Gimli did with those strands?

They became a hairloom of his family.