I only sing karaoke on cruise ships
I think the "only cruise ships" rule has to do with the sense of complete removal from everyday life; karaoke is something so totally outside my "normal" personality that it only works when I can't leave the bar and go home after I'm done.
Safety Dance by Men Without Hats
This was probably the best one I've done. I know the lyrics backwards and forwards so I could concentrate more on singing and less on keeping up with the screen.
Cherry Poppin’ Daddies by Zoot Suit Riot
This one was a lot of fun with good audience response, up until the scat verse. Then I froze.
Paradise City by Guns ‘n Roses
First karaoke song I ever did and it established my rule of only singing karaoke on cruise ships. 1990, DoD-chartered cruise ship in Bahrain harbor. A fellow soldier had suggested I try a White Russian and had quietly told the bartender to make it a double. The result wasn't pretty but I did it.

