鉄板 てっぱんネタじゃなかったです
teppannetajanakattadesu

Noun
Desu Copula

The polite, past negative form of 鉄板ネタ

1. Wasn't a sure thing.; Wasn't a guaranteed hit.; It wasn't a reliable topic.

Past/Perfective
Negative
Polite
Casual Register