Sometimes you're NTA on paper, but you kinda are in real life.
I think the man who's telling this story is bringing an old grudge into it, and I can't pinpoint exactly why. It's something about how he describes the other dude's food preferences, or the way he treats them as childish. Something tells me that if he had ordered something he considered more 'manly,' he wouldn't have reacted that way, but maybe I'm exaggerating.
Don't get me wrong, I completely agree that some food preferences are kind of childish. Some people really didn't explore any taste or texture past the age of eight years old, and there are truly tastes they will never acquire. Their loss, of course. But those picky tendencies, almost always, come hand in hand with personalities that won't shut up about them. They will cause a scene, just like children do.
Not liking a food is one thing, but being entitled enough to think that a young person who's kindly covering the check for a group of people is going to pay for whatever extra thing you order is kinda crazy. I truly believe some people don't grasp the value of money until they're much, much older. They simply don't understand it.
To be fair, it's not that hard to realize you're being impolite for ordering something extra and expecting it to be covered, but this man clearly didn't. The thing is, how the entire story developed- even though the one who was initially covering the check was in the right- he was kind of petty in the end.
He could've been more elegant and not wait until the end, make remarks about how childish were the other dude's preferences, and let him know he wasn't paying. He could've stated that when he realized what was happening, but I get it; things might have escalated too quickly.
The thing I can't forget is that they're almost the same age; how could the 25-year-old ordering the nuggets not realize he was overstepping the line?