I got the perfect solution!!
Here's what you do, you INSULT it.
How to insult a whistling toilet, first pee in the toilet, then:
1) get a musical instrument, like a guitar or something;
2) play in rythem with the whistling toilet; and
3) once the toilet gets comfy with the music/rythem, you change the music.
This will cause the toilet to really get upset and out of key, then YOU FLUSH
That should do it. The toilet will be soo pissed like.
I hope that works for yah.