My niece used to live with me, and we played the knocking on the bathroom door as a joke as well. we’d yell, room service - need TP for your bun hole? Ok, kind of crude, but when done with a dialect it was hilarious. (I think the bun hole remarks was from Beavis & Butthead).
LOL! Of course, now I hear it in Beavis & Butthead voices, complete with the goofy laughing.