Every time my fiancé and I come home and we bring back food or something for ourselves his mom goes "where's mine?" Or…

Every time my fiancé and I come home and we bring back food or something for ourselves his mom goes "where's mine?" Or "what did you get me?" It's seriously the most annoying fucking thing ever. And today we didn't reply to her and she was like "just ignore me then" all pissy like. I'm sorry but after a while it's not funny anymore and we aren't obligated to buy you anything. Granted once in a while we do.