If I felt that strongly about a dinner of beans there is only one answer for me.

If I was ahead of the other person, and could see that the other person was heading for it, I would grab it as swiftly as possible. Once I had it in my posession, I would then relax and be human and sympathetic. If there was any reason for furthur conversation, I would explain honestly how I really wanted the beans. Its unlikely that the other person would feel that "bean mad" and would only think of me as a bit of an eccentric (and would be right). If he or she felt as strongly about beans and explained it to me, I probably would be convinced to share them, but I wouldn't give them up.

If I was behind in the battle to reach the beans the problem becomes more complex but the basic approach would be much the same - go for it and use any technique short of physical attack and especially telling the other person how important the beans really were to me. Most of the time I would end up with the beans because most of the time the feelings of the other person are not that intense.