How old do you need to be before having temper tantrums is no longer socially acceptable? Ten? Five? Any age over two?
I'll tell you when it is certainly not acceptable. Adulthood. By that point, we expect everyone to know how to deal with any problems that might arise, or at least give the illusion of knowing how to handle things. That isn't to say people don't have a right to get hungry or upset. Just that we expect you to handle it with some degree of grace.
That doesn't seem like too much to ask for, but the following people seem to disagree.