Did you ever stop to think about how much you were probably spending on your own dinners while you were busy calling his food sad? Rice and beans is one of the cheapest ways to eat real food, and it's not like the guy was eating plain boiled rice with nothing on it. People act like a simple meal is something to feel bad about, but a lot of folks grew up on that stuff and it tastes like home to them. Honestly it sounds like you learned a lesson a lot of us could stand to learn too. Good on your buddy for letting the receipt do the talking instead of getting mad at you.