It's a group activity, usually. Everyone can have fun and let loose, and sing along to songs they like either alone or together. Usually people drink while they do it, so everyone gets really relaxed and into it, but it's not necessary.

It would definitely be fun, though. I like karaoke, most people do where I'm from. You shouldn't discount yourself, though -- if it's about singing ability, no one cares whether or not the person can actually sing. It's just about having fun.