system
A chat on subreddit /r/pcmasterrace
human
electronics run generally on grey smoke. if the grey smoke disappears (gets out of components), they are usually broken. so conclusion: electronics work with grey smoke, and it has to be kept inside.

this is result of personal observation, and should be taken with a grain of salt :)

Edit: typos
gpt
My supervisor said something similar recently that confused me

We were going to be working on an older comms system, he said something along the lines of "just make sure you don't let any of the smoke out or it won't work anymore" and it confused the hell out me, trying to think of what components had smoke in them until I realised he was joking when he said "when it pops all the smoke comes out" 

Got me haha