Calvinball

Other kids' games are all such a bore!
They've gotta have rules and they gotta keep score!
Calvinball is better by far!
It's never the same! It's always bizarre!
You don't need a team or a referee!
You know that it's great, 'cause it's named after me!

—The Calvinball theme song^[50]

Calvinball is a game played by Calvin and Hobbes as a rebellion against organized team sports; according to Hobbes, "No sport is less organized than Calvinball!"^[51] The game was introduced in a three-week story in 1990, where Calvin is bullied into signing up to play baseball, cursed when he proves a poor player and insulted when he quits.^[51] Calvin and Hobbes usually play by themselves, although Rosalyn plays once in return for Calvin doing his homework, and does very well for herself after eventually realizing that the rules are made up on the spot.^[52] Most games that Calvin and Hobbes play eventually turn into Calvinball.^[53]

The only consistent rule is that Calvinball may never be played with the same rules twice.^[54] Scoring is also arbitrary, with Hobbes reporting scores of "Q to 12" and "oogy to boogy."^[55] The only recognizable sports Calvinball is similar to are the ones that it emulates (i.e., a cross between croquet, polo, badminton, and volleyball.) Equipment includes a volleyball (the eponymous "Calvinball"), a soccer ball, a croquet set, a badminton set, assorted flags, bags, signs, and a hobby horse. Other things are included as needed, such as a bucket of ice-cold water, a water balloon, and various songs and poetry.^[56] Players also wear masks that resemble blindfolds with holes for the eyes.^[52] When asked how to play, Watterson states, "It's pretty simple: you make up the rules as you go."^[57] Calvinball is a nomic (self-modifying game), a contest of wits and creativity rather than stamina or athletic skill, where Hobbes (and on one occasion, Calvin's baby-sitter, Rosalyn) usually outwits Calvin, who takes it in stride, in contrast to his bad sportsmanship when he loses other games.

via en.wikipedia.org