everyone and his brother

idiomatic

(idiomatic) A large number of people; most people.

Japanese Meaning

大勢の人々 / ほとんどすべての人 / 誰でもかまわず、多くの人

When the new cafe opened, everyone and his brother showed up to try the pastries.

新しいカフェがオープンしたとき、誰も彼もがペストリーを試しにやって来た。

Sense（1）

(idiomatic) A large number of people; most people.