noun
idea notebook; material notebook
Primarily used by comedians, writers, or performers to jot down jokes, stories, or material ideas.
芸人はいつもネタ帳を持ち歩いている。
Comedians always carry an idea notebook with them.
noun
performance log; backstage notebook
A notebook kept backstage at entertainment venues to record the day's acts, preventing repeated material.
楽屋のネタ帳に今日の演目を記入する。
They record today's performances in the backstage notebook.
ネタ refers to the material, idea, or topic itself, while ネタ帳 is the notebook where such material is recorded.
Compound of ネタ (material, idea, from reversal of 種) and 帳 (notebook).