There are few things in my house that I take full possession of and will go full-on war mode if someone violates my ownership. One such item is in my freezer – MY ice cream!
Everyone has their favorite flavor. Mine is coffee. In my house, no one else's favorite flavor is coffee. So if they're eating MY coffee ice cream, it's not their first choice and they shouldn't be. I don't want to have to go stomping around my house asking "Who ate my ice cream?"
If your favorite is vanilla, I say bad choice. Vanilla is the only neutral flavor and anybody's property. You can't claim vanilla. All the other flavors can be claimed. Some people think they can claim Vanilla Bean – Nope!
Once in the freezer, MY ice cream is not community property. If I have to, I'll get out my Sharpie and scribble my name on the carton with a warning- "Stay the fuck away from MY ice cream!". Now, if someone comes to my house and expresses their love of coffee ice cream, and we bond, I'm all for sharing, but of course that would be on my terms.
You can borrow a sweatshirt, wear my slippers, throw on my Red Sox cap, all without asking, but don't go near MY ice cream!