and the Jews are very good at it (they'd have to be, being at the bottom of humanity's status heap for AGES...their great book of humour spawned three major world religions that have had a tremendous effect on humanity -- now THAT'S a good joke...)

so here are some of the ones that I've heard over time (feel free to give your own)

A rabbi and a minister decided to buy a new car together.
The day after they bought it, the rabbi found the minister driving it.  The minister explained that the had just gone to the carwash because, in his religion, it is customary to welcome a new member with the rite of baptism.
The next day, the minister discovered the Rabbi cutting the end of the tailppe.

Martin Lewis converts and becomes a priest.  He gives his first Mass in front of a number of high ranking priests who came for the occasion.  At the end of the new priest's sermon,  a cardinal goes up to congratulate him.
"Pastor Lewis," he said," That was avery weell done, you were just perfect.  But next time, please don't start your sermon with "Fellow Goyim..."

Medical experts from Sudbury have published a paper that concludes that Seder participants should not eart both chopped liver and charoses.
Their research shows that iifi they do, it can lead to Charoses of the Liver.

Moishe walks into a post office to send a package to his wife.
The postmaster says, "Ths package is too heavy, you'll need another stamp."
Moishe reples, "And that should make it lighter?"

Howard, a young gay man telephones his mother.
"Mom, I've decided to go back into the closet.  I've met a wonderful girl and we are going to be married.  What do you think of this news?  You'll be happier now -- I know that my gay lifestyle has been very disturbing to you."
She responds, "I'm, very glad, Howard.  I suppose it would be too much to hope that she's a Jewish girl?"
Howard reples, "Not only is she Jewish, mom, but she comes from a wealthy Bever;ly Hills family."
"So what's her name?" the mother asks.
"Monica Lewinsky," replies Howard.
There is a pause, then his mother asks, "What happen to that nice black boy you were dating last year?"

A Rabbi took a job at a Duracell factory.  His job is to stand on the production line and as the batteries go by, say, "I wish you long life."

Sadie tells Maurice, "You're a schmuck!  you always were a schmuck and you always will be a schmuck!  You look, act and dress like a schmuck!  You'll be a schmuck until the day you die! And if they ran a worldwide competition for schmucks, you would be the world's second biggest schmuck!"
"Why only second place?"  Maurice asks.
"BECAUSE YOU'RE A SCHMUCK!"

Moshe's mother, Hette, once gave him two sweaters for Hanukkah.  The next time Moshe visited his mother, he made sur he was wearing one of them.
As he entered her house, instead of the expected smile, Hette said, "What's the matter, Moshe?  You didn't like the other one?"

Ben Levy was in a hospital ward with two non Jews.  On his first morning, Ben puts his tefillin around his arm, but the non Jews can't figure out what he is doing.
Finally, one says to the other, "Look how smart those Jews are!  He's taking his own blood pressure."

Solly took his King Charles spaniel dog to the vet.  "Doctor Cohen," he said sadly, "I'm afraid I'm going to have to ask you to cut off my dog's tail."
Dr Cohen stepped back in shock, "Solly, why should I do such a terrible thing?"
"Oy vey, my mother-in-law's arriving tomorrow, and I don't want anything to make her think she's welcome."

Moshe was talking to his psychiatrst.
"I had a weird dream recently," he said. "I saw my mother but then I noticed she had your face."
"I found this so worrying that I immediately awoke and couldn't get back to sleep,  just stayed there thinkiing about it until 7am.  I got up, made myself a slice of toast and some coffee and came straight here.  Can you please help me explain the meaning of my dream?"
The psychiatrist kept silent for some time, then said, "One slice of toast and coffee?  Do you call that a breakfast?"