Most well-known sex joke?

Doubtful. “The X needs Y’ed” is a construction native to the Pittsburgh dialect. Most other Americans would say “The X needs Y’ing”, “The X needs to be Y’ed”, or “You should really Y the X”.

ETA: I could see where this joke would be popular elsewhere, but the punchline wouldn’t have the same specific sentence structure, is all I’m sayin’.

Everything fetus said, ETA included.

Man finds out his wife is cheating so he finds a hitman and offers him $20,000 to knock her off. Hitman does some recon work and finds out she’s over at her co-workers house. So they both go off to the coworkers house and the hitman sets up across the street…

Hitman asks the husband, “So what do you want.”

Husband says, “Well take her out then shoot him in the nuts.”

The hitman says OK, so he takes aim with his sniper rifle and…BAM. He then breaks down his scope and starts walking off.

Husband says, “WAIT! YOU WERE SUPPOSED TO DO BOTH!”

Hitman says, “Yeah, I got 2-for-1 in that shot.”

Do you smoke after sex?

I’ve never tried to light it.

Rectum? Damn nearly killed 'im!

“But ye shag just one sheep…”

“What you mean, ‘wrong fucking hole’?”

Kiss you? I shouldn’t even be doing this!

Getting crabs.

Shoot the dog! Shoot the dog!

Regards,
Shodan

“That’s not my belly button!”
“That’s okay- it’s not my finger.”

The one about the man from Nantucket is a limerick and not a joke, but I think it’s famous enough to be worth mentioning.

The version of the traveling salesman & farmer joke with the three holes in the wall is well-known enough to have been made into a Jack Black musical on Mr. Show.

I’ve heard it a lot in Iowa, and I recently heard it in Maryland. So it may be a lot more widespread than you think.

End hijack.

“Don’t tell me you’ve got golf clubs in there!”

I think “that’s what she said” takes the cake. It fits in so many places (that’s what she said!) and literally EVERYONE has heard it. Say “that’s what she said” whenever you hear someone talk about “it” being “hard”, or “keep it up”, especially.

My friend interjects “…as the bishop said to the altarboy” in such situations.

Well, this morning I was in a rush so I just had toast and coffee.

I was told that that was the most common joke among Boston cabbies.

Of course, that was said to me by a Boston cabbie. Guess where he was taking me.

On a scale of one to ten…

…how old is Michael Jackson’s boyfriend?

…pluperfect subjunctive

So who hasn’t heard -

Milk, Milk Lemonade ?

Push the buttons, pull the chain, out comes the chocolate choo choo train.

“Round the corner fudge is made” is the way I heard it.