New cabin boy starts on a ship. That night the captain orders the boy to his cabin.

Now says the captain "I want you to drop your trousers and stick your head out of that port hole." Without question the boy does as he is told .A moment or two later the cabin boy lets out a yell "Hold still" said the captain "its only the roll of the boat." Thank god for that says the cabin boy "I thought it was a roll of carpet."