A rabbi, a priest, and a minister walk into a bar. The bartender asks what he can get them.

The minister says, "nothing for me, I don't drink."

The rabbi says, "nothing for me, I should be getting home to my wife."

The priest says, "nothing for me, I have to think up a punchline."

Why did the blond feed pizza to her dog?

Because blonds are stereotypically regarded as dim-witted, and feeding pizza to a dog is a foolish thing to do, barring some extenuating circumstances.

What's the difference between a leopard and the Prime Minister of Canada?

A lot of things. For one, the Prime Minister of Canada is not, at present, a leopard. In fact, he is not a jungle cat of any sort. I'm fairly certain jungle cats can't hold political office in Canada, although I'm not really an expert on Canadian election law.

How many StackOverflow users does it take to screw in a light bulb?

Hopefully one. I mean, it's not particularly difficult to screw in a light bulb, right?