This is a fun challenge! 'A song you would sing at a karaoke night'.
I've done karaoke a handful of times much to everyone else's disgust. I've been very drunk and I apologise to anyone that was forced to listen.
'Summer Nights' by Danny, Sandy and friends is awesome though. I have sung this before and I was Danny. I'd so do it again. And him. Danny not John. Not John now anyway.
Check out the video below too. It's a Lego Stop Motion Animation. Epic.