I have a housemate who seems to think it's socially acceptable to eat/drink our stuff as long as he replaces it afterwards.
He admitted to eating my other housemate's tomatoes a few weeks ago when my housemate noticed they were missing. He then said he was going to replace them first thing in the morning but it slipped his mind.
Saturday night he knocks on my room door and asks if the cider on top of the fridge was mine. I say yes and he casually replies (with a tone as if he's simply asking about my day) "I drank one, I'll replace it tomorrow."
Well, he does indeed replace it but then proceeds to drink the replacement bottle he bought and message me, "Hi I'll replace the cider tomorrow."
I know me being silent about it isn't helpful (I'm one of those "avoid all conflict" types of people which is an issue I'm trying to fix). I will calmly, firmly ask him to just ask in future.
However, a friend I told about this said that they didn't think it's much of an issue, since it's only small stuff he's stealing and "at least he's replacing it, lots of people steal and never give back".