A Rabbi and Priest are sitting together on an airplane...

and they start chatting about religion, each one comparing their religion. Jesus this and Moses that... we eat Matzoh, and we have the wafer... Christmas and Hannukah and so on.

After a while of politely chatting, the Priest turns to the Rabbi and asks: "So tell me Rabbi... what is the single worst thing that you can do in your religion?”
"Well, for us Jews" answers the Rabbi "the single worst thing we can do is eat pork."
"Ah, I see" answers the Priest, before hesitating and turning to the Rabbi with a quizzical looks in his eyes "And tell me Rabbi, have you ever tasted pork?"
The Rabbi looks around to make sure no one is hearing and answers: "Well, there was this one time. I was visiting the state fair and I saw this huge pan of Bacon, and I just couldn't resist..."
The Priest looks at the Rabbi with understanding and asks “So how was it?”
“Pretty good” answers the Rabbi.

The Rabbi then turns his head to the Priest, cocks and eyebrow and asks "And what about for you guys?"
The Priest thinks a moment before answering "Well... for us men of the cloth, really the worst thing we can do is to lay with a woman."
Suddenly the Rabbi's eyes pique with curiosity "And did you ever...?"
“There was this one time” admits the Priest “where they was this beautiful nun, and I just couldn't resist..."

The Rabbi smiles with great understanding, looks at the Priest in the eye and says "It's a hell of a lot better than pork, isn't it?"