Quoted By:
Leave shit in the toilet and don't flush
But only when she's there
Bonus if you have the opportunity to frame it like she's the one doing it and convincing your roomate it's her and she's lying to him about it
Use arguments like "Dude this wasn't a problem til she came around wtf"
And start it off with something like "man what the hell why do you keep leaving shit in the toilet learn to flush!"
If ever you find out she's on her period and she leaves a feminine product in the garbage (likely it'll be well wrapped in TP), unwrap it and leave it in the toilet (don't flush). Add piss or shit and show your roommate it. Get mad and say something like
"I've been trying to deal with the fucking shit but fucking tampons? " and mention they clog the piping as part of why that can't happen
She'll swear it's not her, but assuming there are no other females in the house, it'll just look like she's lying. He'll want to believe her but assuming you press the point enough, your argument will seem more logical and it'll be harder to believe you'd go to such disgusting lengths just to frame her
Gods speed