Today’s cute and useful Japanese expression is:
あっという間
atto yuu ma
Literally, it means “while saying Oh!,” or “in the time it takes to say Ah!”. And it is used to say “very short” or “very quickly” (if you ad “ni” at the end), because we just have the time to say “Oh!”!
It’s interesting, in English the equivalent would be “in the blink of an eye,” which is the same in French “en un clin d’oeil“.
I like the Japanese expression because it really catches well the image of rapidness, it’s almost as if you can visualize the time passing fast, like when you see pass an express train. “あっ” in Japanese is an interjection used when we are the surprised, like “oh!” or “hey!’ in English.
You can use it like that, for example:
夏休みはあっという間に過ぎました。（natsuyasumi wa atto yuu ma ni sugimashita.）
The summer vacation went by very quickly. (in an instant, ended too soon, etc.)
パーティは楽しすぎて、あっという間でした。(paatii wa tanoshisugite atto yuu ma deshita.)
The party was so fun that it passed by as quick as a flash.