Most Helpful Guy
Talk to them about it first. Not good to ignore your boss.
If that doesn't work, then go to their boss. Then to HR.1
Most Helpful Girl
You're not supposed to ignore the boss if you wanna do well in the company.1
Talk to his superior and than start ignoring him when ever he crosses his limits. If need be , show your opposition to his wrong behavior. Just ignoring will not help. Take some actions to put an end to this practice once and for all.
Don't ignore.. Look them in the eye and tell them "will you please let me take a fucking shit in peace, you annoying idiot". Might get you fired though. Or just start groaning when you're in the bathroom. But do tell them that it's inappropriate.