Through the pitch-black night, the captain sees a light dead ahead on a collision course with his ship.

He sends a signal: “Change your course ten degrees east.”

The light signals back: “Change yours, ten degrees west.”

Angry, the captain sends: “I’m a Navy captain! Change your course, sir!”

“I’m a seaman, second class,” comes the reply. “Change your course, sir.”

Now the captain is furious. “I’m a battleship! I’m not changing course!”

There’s one last reply. “I’m a lighthouse. Your call.”