I totally do a bunch of routine things with my eyes closed - I think it's just to reduce visual stimuli for predictable sights, like washing my hands, typing, putting pieces together, getting dressed, taking a shower... Saving up so I don't overdo my visual input quota.
My favorite for closed eyes is morse code; I do ham radio and am practicing that, so I can listen to a book in morse code and transcribe it into the computer for practice. Since I use vim as an editor, I get worried that I'll end up in the wrong mode and lose some keystrokes, that hasn't happened yet.
I wouldn't ever hope to be blind but it would be nice to spend a whole day in the dark.
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I swallowed a bug.