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 10 degree east.” The light signals back: “Change yours, 10 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 is one last reply “I’m a lighthouse Your call.”