気が抜けちゃったよ。

spirit; mind; heart; nature; disposition; motivation; intention; mood; feelings; atmosphere; essence

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

to come out; to fall out; to be omitted; to be missing; to escape; to come loose; to fade; to discolour; to wear a hole (e.g. clothes); to leave (e.g. a meeting); to be clear; to be transparent (e.g. of the sky); to be stupid; to be absentminded; to be careless; to be inattentive; to exit (a program loop)

indicates certainty, emphasis, contempt, request, etc.; used when calling out to someone; used to catch one's breath or get someone's attention; yo!