Calvinball
A game or activity where one player makes up the rules, can change the rules at any time, and doesn't have to tell you the rules (unless you break a rule, of course).
The Supreme Court Is Playing Constitutional Calvinball
Calvinball
game in which there is only one rule, that being "you cannot repeat any action."
"Baseball is so organized. We should go play Calvinball!"
"Nothing is less organized than Calvinball."
"Nothing is less organized than Calvinball."