expression
of all times; of all days
Expresses exasperation or irony that something happens at an especially bad or inconvenient moment. Often followed by a negative or undesirable event.
折もあろうに、大事な会議の日に限って電車が遅れるなんて。
Of all days, the train had to be late on the day of an important meeting.
折もあろうに、彼が訪ねてきたのは引っ越しの真っ最中だった。
Of all times, he came to visit right in the middle of moving.
Neutral 'at that time'; lacks the ironic or exasperated nuance of 折もあろうに.
From 折 (opportunity/time) + も (even) + あろう (volitional of ある) + に (particle), literally 'even though there must be other times'.