I don't do karaoke because I can't carry a tune with a bucket. And if I did, like everything I'd want to do they wouldn't have. In an alternate universe I'd love to karaoke Mercyful Fate's Into the Coven or Judas Priest's Dreamer Deceiver.
The singer in my band often does karaoke, but I never get to see him do it, because he does it on nights I work, and nights I don't work we're doing band practice.
In our last band, he'd sometimes karaoke with our former bandmate's equipment, and we had a VERY happy accident. Despite the fact we worships Ronnie James Dio, until last year he had never attempted to sing any Dio song before (any band Dio was in). One night at practice he was karaoking Heaven and Hell's Atom and Evil. He was singing very low pitched, which at that point I had never heard him do, and I was entranced. He said he never sang like that before, he only did it because Dio has a higher register than him, and the only way for him to sing in the correct key was to go an octave lower. I was like, "dude, you got to do that in our music." In that particular band I don't think that ever happened because he only sang on songs our singer before him wrote. Now in our current band, he does some vocals like that in the song we are currently working on.