Drugs and alcohol and inappropriate times for inspiration

For me it depends on what kind of music and instrument I'm playing.
If I'm playing metal with the guitar, I'd rather be sober.
But when I'm playing drums with my stoner/space rock band, I do enjoy being high, as we tend to do a lot of jams, and while stoned we usually come up with cool stuff.
 
Cooler drum parts tend to come to me when I'm stoned on weed, but I usually make poorer mix decisions and I can't physically play the guitar as well.
 
Whenever an idea comes to me (most likely at some random moment one doesn't expect, as you point out) I hum/tap/sing the rhythm, lyrics or the notes on the cellphone's recording app. So, at the end of the day I can record them more properly and permanently.
Kind of awkward at first but nowadays I'm very used to do it, I've gotten the hang of it as not to get unintelligible clipping nonsense.


This!!!! I tend to come up with melodies, rhythms, and riffs while driving so my phone is always a handy way to capture an idea. I have a dashboard mount so it's always just a foot away with a shortcut for the recording app on my home screen.

All of it goes into my DropBox account and when I get home if I still find it inspirational I work on it.