I recently got a call from one of my best friends from high school, who happened to be back at his parents’ house and was remembering times we had spent together hanging out there. We caught up and talked about mutual friends and whatnot, and we recalled all the significant late night conversations that took place around their kitchen table. I mentioned to him that awhile ago I had come across the book Refrigerator Rights, which talks about how real community, friendship and hospitality can be measured by the degree that friends have "refrigerator rights," the comfort level and freedom to just open up the fridge and feel welcome to use things there without asking.
My friend's parents really modeled this for us. They would insist that any of us high schoolers should feel free to get pop or juice from the fridge and snack on whatever was around. This seemed odd at first, but soon became normal for us. And much of our friendship and community was facilitated by the food and hospitality symbolized by open access to that refrigerator.
It seems to me that one easy way to offer refrigerator rights is that the next time you have people over, in addition to asking, "Can I get you anything?" you could also say, "Feel free to get whatever you need from the fridge." And don't get freaked out if people take you up on it!