expression, interjection
that was a good one!; good pun!; what a stinger!
Humorous interjection used to praise a witty remark, especially a pun or sharp retort. Originates from the TV show 笑点, where a cushion (座布団) was awarded for clever answers. The literal meaning 'one zabuton' is the source of the phrase but is not used literally in this expression.
See also: 座布団
A: 「布団が吹っ飛んだ！」 B: 「座布団一枚！」
A: "The futon blew away!" B: "That was a good one!"
彼のダジャレに、思わず「座布団一枚」と言ってしまった。
At his pun, I couldn't help but say, "Good pun!"
座布団 is the literal 'zabuton' cushion. 座布団一枚 is a set phrase used as an interjection, not a literal count of cushions.
From the long-running TV show 笑点, where a zabuton cushion was given as a prize for a witty answer. The phrase is now used humorously outside the show to praise a clever remark.