of all things

idiomatic often used as a sentence adverb

(idiomatic) Especially; more than other things. / (idiomatic, often used as a sentence adverb) Surprisingly.

Japanese Meaning

(慣用句) 他のすべての物事に比べて特に際立っている、あるいは驚くべき様相を示す表現 / (口語的に文頭で用いられる副詞的表現として) 驚きを表す

He chose, of all things, a bright pink tie for the funeral.

彼は、こともあろうに葬式に派手なピンクのネクタイを選んだ。

Sense（1）

(idiomatic) Especially; more than other things.

Sense（2）

(idiomatic, often used as a sentence adverb) Surprisingly.

He reached into his pocket and pulled out, of all things, an ice cream cone.