also: バタンキュウ
noun, adverb taking the 'to' particle
falling asleep immediately; going out like a light
Colloquial onomatopoeia for collapsing into bed and instantly falling asleep, often from exhaustion. Combines バタン (sound of flopping down) and キュー (suggesting a sudden stop or sleep).
See also: 巴丹
I got home and crashed right into bed.
I'm so tired I'll be out like a light as soon as I hit the futon.