I think everyone is aware that she is gluten free and even if she isn’t if it’s a special diet then it’s common courtesy to ask and eat. Colitis is very serious if she suffers from it and lactose free as well. I only eat lactose free as I am allergic to dairy - it can lend me in the hospital so if anyone touches my food it p****s me off something bad. I can see why she reacted that way. As a joke once someone drank my oat milk and changed it with normal milk and I realised it immediately but got severe rash and had to be rushed into emergency. Sometimes joke can backfire, Plus, it’s juvenile too to eat someone’s special diet when they do get their own supply.