過か去こ一いち

adverb, noun

most ... ever; most ... up to now; more ... than ever before

Slang abbreviation of 過去一番 (かこいちばん). Used adverbially or as a noun to express that something is the most extreme in one's experience up to now. Often followed by an adjective or adjectival noun.

• このラーメン、過か去こ一いちうまい！

  This ramen is the best I've ever had!

• 今日きょうのテスト、過か去こ一いち難むずかしかった。

  Today's test was the hardest ever.