Calvinball Calvinball is a game played almost exclusively by Calvin and Hobbes as a rebellion against organized team sports (like baseball), although the babysitter Rosalyn plays on one occasion. Calvinball is played with whatever implements are available, often a volleyball (referred to as the "Calvinball") and a croquet set, and the rules are invented as the game goes along. The only consistent rule is that the playing rules can never be the same for two games. Calvin and Hobbes wear masks similar to The Lone Ranger's and Zorro's while they play. Calvin tells Rosalyn that another rule is that "no one's allowed to question the masks", but as this is the only time it actually comes up, it may simply be one of the ad hoc-invented rules. Either player may change any rule at any time (with the exception of those rules stated above). Scoring is also entirely arbitrary: Hobbes has reported scores of "Q to 12" and "oogy to boogy." Calvinball is essentially a game of wits and creativity rather than purely physical feats, and in this Hobbes is typically more successful than Calvin himself. It is often regarded as an example of nomic. In the Tenth Anniversary Book, Watterson states that the greatest number of questions he receives concern Calvinball and how to play it. He then answers the question once and for all: "People have asked how to play Calvinball. It's pretty simple: you make up the rules as you go."