Two guys rented a boat and go fishing. They found a great spot and caught tons of fish all day. Just fish after fish.
Finally when it was getting late, one guy turns to the other and says "Wow this is the greatest fishing spot ever! We should put a big ''X'' in the bottom of the boat to mark this spot for next time."
The second guy turns to the first and says "Wait just a second. What if we don't get the same boat?"