I used to work for a chain of video game stores that takes trade-ins on a regular basis. We offered cash for games (at a reduced rate) but could only give cash to people over 18. I believe it had something to do with pawn laws that we had to follow.
Anyway, a kid, who I'm guessing was between 15 and 17 years old comes in with his older brother one day. He's got a stack of games in his hands (some of them brand new) and informs me that he plans on trading them in.
I ask him to head over to the counter and proceed to check over the games. A few of them are scratched to what I would consider to be beyond repair, but were still within the guidelines that allow me to accept them as trade. After I finish, I tell him that he can go ahead and look around and I'll have his transaction waiting for him when he's done.
After a couple minutes he comes up to the counter and says he wants cash for the games. I was familiar with this young man and was pretty sure he wasn't over 18, but I asked him for his ID anyway. As I suspected, he was underage.
ME: "I can't give you cash for your games as you're under 18, but I can give you store credit if you like. You can use it later when you find a game you want."
He turns and looks at his brother and then agrees. I swipe an empty gift card through the register and he walks away with something like 15 or 20 bucks in store credit. He leaves with his brother and I move on with my day.
Less than an hour later, he comes back in and is pretty mad. He's saying his card didn't work. My first thought is that he went to the other store in our chain that happened to be less than 10 minutes away, so I ask him.
ME: "Did you try it at the (our-other-location) down the street?"
CUSTOMER: "No, I was at (big-box-retailer-next-door)."
I almost face-palmed. The worst part was it took me about 30 minutes to explain to him why he couldn't use his store credit for our store at a different store.