〜ではあるまいし
Formation
Meaning
Used to express that since a certain person, situation, or status does not exist, the current behavior or feeling is inappropriate or excessive.
Note
Commonly used when rebuking, advising, or giving an excuse. It implies that the current state of affairs is unreasonable given the facts. The variant '〜じゃあるまいし' is a more casual, spoken version.
Examples
子供ではあるまいし、そんなことで泣くな。
You're not a child, so don't cry over something like that.
神様ではあるまいし、未来のことなんて分かるわけがない。
I'm not a god, so there's no way I can know about the future.
新人でもあるまいし、こんな初歩的なミスをするなんて。
You're not a rookie, so for you to make such a basic mistake...
宝くじに当たったわけでもあるまいし、そんなに贅沢はできない。
It's not like I won the lottery, so I can't afford that much luxury.
他人じゃあるまいし、遠慮しないで何でも言ってよ。
We're not strangers, so don't hesitate to say anything.
仕事じゃあるまいし、そんなにきっちり時間を守らなくてもいいよ。
It's not like it's work, so you don't have to be so strict about keeping time.