こともあろうに

expression

of all things; of all people; of all places

Expresses surprise, disbelief, or criticism that something or someone is the last thing you would expect in a given situation. Often used as a set phrase at the beginning of a sentence.

• 事こともあろうに、彼かれは会かい議ぎ中ちゅうに居い眠ねむりを始はじめた。

  Of all things, he started dozing off during the meeting.

• 事こともあろうに、こんな大だい事じな日ひに限かぎって電でん車しゃが遅おくれるなんて。

  Of all days, the train had to be late on such an important day.