"Small Head" joke

A guy goes into a bar and orders a beer. He happens to look down the bar and sees a man with a head the size of a cue ball sitting there, so he walks down and says to the man, "Excuse me, sir, I don?t mean to be rude, but I noticed you have a small head. Is this a birth defect?"

The man says, "No, I got this in the war. My ship was torpedoed by the Germans in WWII. I was the only survivor on the ship, so I swam to shore."

"Then 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."

"What she'd say," the curious stranger asked.

"She said, "I can't grant that wish, because mermaids can't have sex.'"

"So," continued the old man with a dejected look on his face, "I said,' How about a little head?'"