Wiktionary
n. A particular children's ball game played against a wall with a tennis ball.
Wikipedia
Patball is a non-contact competitive ball game played in many forms using one's hands or head to hit the ball against a wall - the objective being to get the succeeding player out. The game is popular in school playgrounds during break-time. Patball is played with a tennis ball, or other similar-sized specific patball, and the preferred hand, rather than any form of racquet or bat. The hand is used to "pat" the ball at the wall with the objective of making the ball un-returnable, similar to squash. In some variations of the game the use of the foot is also allowed.
The sport was supposedly invented by Dulwich college but many people dispute where it came from as it is now played in many areas.
It is very popular among London public schools, most notably, Dulwich College and Dulwich Hamlet.
Usage examples of "patball".
Not even this release — or injection of balance — is available to Kepesh: he is lost in a truly lugubrious solipsism, a mere patball of the neuroses which stride unchallenged through his psyche.