Noun
Calvinball (uncountable)
(games) A deliberately absurd sport without rules.
The only permanent rule in Calvinball is that you can never play it the same way twice! (Calvin) Bill Watterson
Calvin remarks that "sooner or later, all our games turn into Calvinball", Watterson (2005). vol. 3, p. 438. Comic originally published 1995-09-24. Source: Internet
Calvinball was first introduced to the readers at the end of a 1990 storyline involving Calvin reluctantly joining recess baseball. Source: Internet
Calvinball is better by far! Source: Internet
In Rosalyn's last story, she is revealed to have in common with Calvin a sense of imagination, and the two of them play Calvinball with Hobbes. Source: Internet
The only hint at the true creation of the game ironically comes from the last Calvinball strip, in which a game of football quickly devolves into a game of Calvinball. Source: Internet