Have you heard this one?
An infinite number of mathematicians walk into a bar.
The first one orders a beer.
The second one orders half a beer.
The third one orders a quarter of a beer.
The bartender interrupts the fourth: “How about I just give you 2 beers and let you all work the rest out.”

And another thing:
This atom walks into a bar. He says to the bartender, “I think I lost an electron here last night.” The bartender says, “Are you positive?”
Atom says: “No, I’m reduced.” Bartender says: “No charge.”

I guess not everyone will see the humour, but it sure tickles my funnybone.