In all seriousness (without any helicopter jokes or anything), should those who don't believe in private property be forbidden from owning private property? As far as I'm concerned, from an ethical standpoint, the second you say that private property doesn't exist, you aren't allowed to own your self and your own body, so you become no one's property and you lose all rights as a human being. I know Hoppe came up with this, but I never read about how this would work in practice.
The only practical problem I see with this theory is how to correctly determine whether someone is a property-denier or not so as to prevent false accusations and abuse, while also preventing leftists from dodging punishment when (as usual) they lie and pretend to not be the dirty, filthy leftists that they are.