True,gaming laws vary from state to state.I cannot imagine a state law prohibiting Joe from betting Jeorge that he cannot stand on his head longer then him but it is possible especially if there are some outdated and unenforced laws on the books.
I was looking up state gamling laws when I came across this for Virginia.After stating that betting on a contest that one is directly involved in is legal it goes on to say:
Bona Fide Contest
The state of Virginia has no statutory authority over billiards tournaments, nor is there any case law. The state requires all individuals entered in the tournament must enter the contest in the class they qualify or they are guilty of fraudulent activity under the penalty of a Class 3 misdemeanor. The bona fide contest clause allows competitors to play for a prize, purse or premiums if they are involved actively in the game. There are thirteen states, including Virginia, which operates under the bona fide contest clause.
This has nothing to do with the subject but I thought it amusing.