The only time I willingly do that is when I'm browsing the Web while drunk, and something about the page's behavior or design annoys me, so I'll casually open up the inspector and work out a fix.
This has happened several times and I usually end up with a nice snippet of code that's actually useful. Interestingly, I almost never do this while sober, or stoned. There's just something about drinking that makes me more eager to do stuff like that.
For any kind of work beyond that, though, I'm effectively useless when drunk.