One day two blondes rented a row boat to go fishing. They were having a good day catching a lot of fish.
just before they were ready to quit for the day the one sitting in the bow said " this is a good spot. we need to remember this spot tomorrow"
the one in the stern took a marker out of the tackle box and put a large X on the bottom of the boat.
The one in the bow said "whats that for?"
the other said "i'm marking our spot for tomorrow"
The bow rider replied "don't be silly, you can not mark this spot that way"
"why" said the other
the bow rider replied"how do you know we'll get the same rental boat tomorrow?"