I'm guessing a bulletproof couch would just be something for one to hide behind in the event of a shooting in or outside of one's home.
Like, a lot of houses are pretty shoddily built, and a stray bullet from a gunfight out in the street could easily make its way inside and hit somebody in an unhealthy location despite them having nothing to do with said gunfight. I saw it in a movie once. More than once.
I think it's actually a fairly sensible invention for areas with lots of bullets whizzing about.
It would be - if the vast majority of shootings weren't over in seconds, and that you won't even know shots are being fired until after they've all already hit. Sure, the couch would help you if a bullet happened to be heading toward the half of your body protected by it, but if one passed through where your upper body (which contains most of the more important bits) is, it wouldn't do a damn thing.
I don't know, if you were in an area with a lot of gang crime it might be more a case of, "Oh, those assholes are shooting at each other from opposite ends of the street again, better chill behind my couch until they get it out of their system". Obviously if it's some kind of assassination you aren't going to have much couch time.
And of course if someone barges into your house to shoot at
you, your couch probably won't save you.
Unless in some Hollywood moment you manage to dive behind it, preferably in slow motion.