While this is an incredibly moot discussion, I will answer your question, and let it drop.

IN your example, I receive no possessory interest. However if you loan me your car in exchange for something (cash, use of something else, doing you a favor), I then have a possessory interest.

The casino in the bogus event related, gave them the chips for their using some restaurtant or show or whatever it was. They then had a possessory interest. If the casino had said we really like you so we are going to let you hold these chips for awhile, or we'll loan them to you for an unspecified period of time, then no possessory interest attaches.

Back to the example of the car. YOu loan me your car for the weekend for helping you move, Sat morning you change your mind, and come take it. You may be committing a crime, or opening yourself up for civil litigation (admittedly a stupid option for me to exercise, but nonetheless). The lawful way to reassert legal control, as the ultimate ownership interest, over the item would be a writ of replevin.