How to make them laugh--- every time.

I'll give you the formula. The easiest sort of skeleton for a terrible joke is "What is a {BLANK!}'s favorite {BLANK!}?"

The two {BLANK}s, I should indicate, are not intended to represent the same thing. The first is meant to represent one broad subject, and the second is meant to represent a different one that it is possible to link with the first through a narrower subject.

The most humorous answer to the question is a mixture of the two {BLANKS}s in a way that signifies both, but in a meaningless way. Here are examples:

Who is a pumpkin's favorite president?
George Squashington.

What is a podiatrist's favorite meal?
Sloppy toes.

What is a race car driver's favorite sacrifice?
Fasting.

But you can make the exact same joke outside of the "favorite this" or "favorite that" skeleton. Go crazy:

What sort of hat does a pig love most?
A porkpie hat.

Where does a vampire go to deposit both money and an idea vampires are linked to?
The blood bank.

You can think of these really, really quick at parties and receptions if you remember this sort of approach to the joke. If you do it enough, and do not do it in front of the same people too often, it will eventually become likely that you make a joke, everybody laughs, and nobody touches their foreheads.

At which point you coast.