Origins
From the trope of a fix as instant relief, fused with flash for the split-second certainty that arrives like a camera flare.
Meaning
Fixflash is the sudden conviction, in the middle of frustration, that using would solve the entire moment.
The mind produces a clean fantasy of immediate calm, as if the feeling could be switched off. Then reality returns. We remember what using actually costs, and we recognize the new requirement.
We have to stay inside the feeling until it changes on its own.
Usage
Fixflash is that split second where using feels like the obvious solution, then you remember you have to sit with the feeling instead.