to suddenly go to sleep or feel weak because you are extremely tired

I got home and flaked out on the sofa. 我一进家门便瘫倒在沙发上。

to do something strange or not do what you are expected to do

I'm tired of relying on other people - they keep flaking out on me. 我再也受不了需要依赖他人了——他们个个都怪怪的。