At a lake with rental boats, the owner speaks over the loudspeaker:

“Boat number 99, please return to the dock. Your time is up!” A few minutes pass. No boat returns. The owner, louder this time: “Boat number 99, return immediately or you’ll be charged for overtime!” Still nothing. The assistant steps in and says: “Boss… we only have 75 boats. There is no number 99.” After a couple of seconds, the owner grabs the mic again and says: “Boat number 66… everything okay out there?”