A man walked into a bar on a slow night and sat down.

After a few minutes, the bartender asked him if he wanted a drink.  The
man replied, "No thanks, I don't drink,

I tried it once but I didn't like it!"

So the bartender said, "Well would you like a cigarette?"

The man said, "No, I don't smoke, I tried it once but I didn't like it!"

The bartender asked him if he'd like to play a game of pool, and again
the man said, "No I don't like pool, I tried it once but I didn't like
it...  As a matter of fact, I wouldn't be here at all, but I'm waiting on my son!"

"He's an only child, isn't he?" asked the barkeep.

"Yes..!!  How'd you know..??" answered the man.

"Because I'm sure you only shagged his mother once..!!" said the barkeep.