Shameless taken from another site:
An infinite number of mathematicians walk into a bar. The first mathematician orders a beer. The second orders half a beer.
“I don’t serve half-beers,” the bartender replies.
“Excuse me?” asks the second mathematician.
“What kind of bar serves half-beers?” The bartender remarks. “That’s ridiculous.”
“Oh c’mon,” says mathematician #1, “do you know how hard it is to collect an infinite number of us? Just play along!”
“No, you see, there are very strict laws on how I can serve drinks. I couldn’t serve you half a beer even if I wanted to.”
“But that’s not a problem,” chimes in a third mathematician, “at the end of the joke, you serve us a whole number of beers. You see, when you take the sum of a continuously halving function–”
“I know how limits work,” interjects the bartender.
“Oh, alright then. I didn’t want to assume a bartender would be familiar with such advanced mathematics.”
“Are you kidding me?” replies the bartender. “You learn limits in, like, 9th grade! What kind of mathematician thinks limits are advanced mathematics?”
“HE’S ON TO US!” mathematician #1 screeches.
Simultaneously, every mathematician opens their mouth and out pours a cloud of multicolored mosquitoes. Each mathematician is bellowing insects of a different shade.
The mosquitoes form into a singular, polychromatic swarm. “FOOLS!” it booms in unison. “I WILL INFECT EVERY BEING ON THIS PATHETIC PLANET WITH MALARIA!”
The bartender stands fearless against the technicolor horde. “But wait!” he interrupts, thinking fast, “if you do that, politicians will use the catastrophe as an excuse to implement free healthcare. Think of how much that will hurt the taxpayers!”
The mosquitoes fall silent for a brief moment. “My God, you’re right. We didn’t think about the economy! Very well, we will not attack this dimension. FOR THE TAXPAYERS!”
And with that, they vanish.
A nearby barfly stumbles over to the bartender. “How did you know that that would work?” he slurs.
“It’s simple, really,” the bartender says. “I saw that the vectors formed a gradient, and therefore must be conservative.”
