Instead of white-noise or music, why not play the sounds of people using the bathroom? You know like, peeing, pooping, farting, chatter, moans and groans. This way our own noises become indiscernible from the background noise.
Imagine if every time some of your coworkers go in for a little pee pee, you hear "peeing, pooping, farting, chatter, moans and groans" at maximum volume.
You know what ? That sounds like a hella fun workplace. Don’t forget the gross spitting sound.
What if it's the other way around?