hand of 9 and 1 in oicho-kabu
A specific scoring combination in the traditional Japanese card game oicho-kabu, where a 9 and a 1 together form a hand.
See also: おいちょかぶ
In oicho-kabu, when a 9 and a 1 come up, that hand is called 'kuppin'.
Katakana spelling, common in game contexts.
From the numbers 九 (9) and 一 (1), with the reading くっぴん likely derived from a contraction or sound shift of く (9) and いち (1) to くい → くっ, plus ぴん possibly from 一 (いち) influenced by card-game jargon.