I always assume they're one of those whiz kids who invented some cool technological breakthrough that will hurl the rest of us into the future, so I usually honk my horn, shout congratulations and applaud them.
Of course, I could be wrong. They might be on some misadventure like Ferris Bueller or had a lot of plastic surgery done to give them such a youthful appearance.
eta: I'm kidding. I really don't care at all.
However, I knew a really spoiled kid when I was growing up and he told me about this one day toward the end of summer vacation, not long before he became a college sophomore. He called home to ask for a little assistance with his finances so that he could get settled into a nicer apartment and to acquire a few other necessities to make it like home. He requested 20K, which I gathered wasn't uncommon. His dad asked about his vacation and also expressed an interest in his grades. My friend explained that everything was great and that he'd already been getting a jump start on his studies. Then his dad asked where he was calling from and my friend told him that he was looking at a new place to stay at that very moment. His dad told him he was disappointed in his choice to relocate. My friend explained that it was all for the better and that he'd have less distractions in this new place. His dad called him on his shit right there and told his son he was aware the phone call was coming from Colombia and that if this cash request was for bail, it'd be the last of it. Well, it was and that was that. My friend did make it back to schoo just in time, but he had to take several classes over, he had to sell his prized, fancy car to pay for as much as it would cover and from that point on, he paid his own way through school. He changed from studying business to studying law and eventually established a humble practice writing contracts and such. He has a nice car again too. He and his son are fixing up an old 53 Buick that his kid can drive when he gets his license.