Looking for a fic with some limited details

I remember that Harry and Hermione know each other, and Ginny and Hermione know each other but Harry doesn't know that Ginny knows Hermione. Ginny doesn't like Hermione and is a cat animagus, and I'm pretty sure there is a scene where Ginny pees on Hermiones stuff in her animagus form.

If anyone can work out what this fic is from these vague details you'll be my hero forever!