当あたり前まえ田だのクラッカー

Meanings

1

of course!; obviously!

jocular, humorous

Jocular, punning expression based on 当たり前 (of course) and the cracker brand 前田のクラッカー. Used playfully to emphasize that something is obvious.

See also: 当たり前

「明日あしたは日にち曜よう日びだよ」「当あたり前まえ田だのクラッカー！」
"Tomorrow is Sunday." "Of course it is!"
そんなの当あたり前まえ田だのクラッカーだよ。
That's Captain Obvious stuff.