An engineer, a physicist and a mathematician were asked to hammer a nail into a wall.
The engineer went to build a Universal Automatic Nailer -- a device able to hammer every possible nail into every possible wall.
The physicist conducted series of experiments on strength of hammers, nails, and walls and developed a revolutionary technology of ultra-sonic nail hammering at super-low temperature.
The mathematician generalized the problem to a N dimensional problem of penetration of a knotted one dimensional nail into a N-1 dimensional hyper-wall. Several fundamental theorems are proved. Of course, the problem is too rich to suggest a possibility of a simple solution, even the existence of a solution is far from obvious.
I thought it was a good joke, even though I didn't understand it fully. like the part about it not even being certain that there is a solution.
Here is a Vermont joke, which involves hammers. (There is even a bit of very, very simple math, so I guess it kinda, sorta qualifies for this site.)
This farmer walks into a hardware store, and buys a hammer for $10. Twenty minutes later, he is back, and he buys another hammer. All day, the farmer keeps coming back to buy hammers. Finally the hardware store owner asks him what he is doing with all the hammer.
"Selling them," replies the farmer.
"Yes, I buy the hammer for $10, and then I go out on the street and sell it for $5."
"But you are losing money each time," says the store owner, puzzled.
"Yeah, I know," replies the farmer, "but it sure beats the hell out of farming!"
Love is what matters most!