“A man who has finally made it in business treats himself to a new Lamborghini. After buying it, he feels guilty so he goes to the Orthodox Rabbi and asks for a mezuzah for the Lamborghini.
“You want a mezuzah for what?” the Rabbi asks.
“It’s a Lamborghini,”
“What’s a Lamborghini?” asks the Rabbi.
“A sports car.”
“What? That’s blasphemy!” the Rabbi shouts. “You want a mezuzah for a sports car? Go to the Conservatives!”
Well, the man is disappointed, but goes to the Conservative Rabbi and asks for a mezuzah.
“You want a mezuzah for what?” the Rabbi asks.
“For my Lamborghini”, the man replies.
“What’s a Lamborghini?” asks the Rabbi.
“A car, a sports car.”
“What kind of sports car?” asks the Rabbi.
“Italian.”
“What? That is blasphemy!” the Rabbi shouts. “You want a mezuzah for a Goyishe car? Go to the Reform!”
Again, the man feels guilty and disappointed, but goes to the Reform Rabbi.
“Rabbi,” he asks, “I’d like a mezuzah for my Lamborghini.”
“You have a Lamborghini?” asks the Rabbi.
“You know what it is?” says the man.
“Of course! It’s a fantastic Italian sports car. What’s a mezuzah?”

This is funny because reformed Jews don’t do anything!

THe person that told me this was basically an agnostic Jew, so I think it is a way of coping with a part form past traditions. It is a humorous acknowledgement of the fact that many reformed Jews are very uninformed about actual Jewish religions and traditions- almost metafolklore, this is. Also, it is dealing with the acknowledgement of the ‘rich Jew’ stereotype with the man having the Lamborghini to begin with.