flake out

flake out (third-person singular simple present flakes out, present participle flaking out, simple past and past participle flaked out)

1. (intransitive, informal) To fall asleep from exhaustion.
2. (intransitive, informal) To flake or be flaky: to prove unreliable; to abandon or desert.

   John said he could drive me to the airport, but then he flaked out on me, and I had to call a cab at the last minute.

• “flake out”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.