“Some Idiot”

If you get into the ocean with things in your pockets, you can’t be totally shocked when the waves knock things loose. For example, your house key might fall out of your pocket. 

This person may have wanted to take a closer look at that key before writing it off as belonging to an “idiot” and chucking it into the waves. It only took hours to realize that he was indeed the idiot who lost their key.