Spear fishing Joke

Two free divers go spear fishing. They shoot a lot of fish and 
return to the shore.
The first one says, "I hope you remember the spot where we 
 caught all those fish."
The other answers, "Yes, I made an 'X' on the side of the 
boat to mark the spot."
"You idiot!" cries the first, "How do you know we will get the 
 same boat tomorrow?"