Mermaid sex

This guy went into a bar and ordered a beer. He happened to look down the bar and see a man sitting there with a head the size of a cue ball.

So he walked down and said to the man,

"Excuse me sir, I dont mean to be rude but I noticed you have a small head. Is this a birth defect??"

The man said "No, I got this in the war. The German in WWII torpedoed my ship. I was the only survivor on the
ship so I swam to shore. One day a mermaid swam up to me and said she would grant me three wishes.

For my first wish I wanted to return to the U.S. The
mermaid granted that wish. My second wish was to have all the money I would ever need. Wish granted. My third wish was to have sex with the mermaid. She said, couldnt grant that wish because mermaids cant have sex.

So I said, How about a little head??