Jason's not very good at relationships - at least, not steady ones. You don't have to buy birthday gifts for a fling. You do have to buy birthday gifts for a lover. That's why when you've been dating for a year, and your birthday rolls around, he's a bit unsure of what to get you.
What would you like? Would at least $1000 be enough, or would that be too much? Similar questions continue to plague him, so, against his better judgment, he goes to Dick for advice. Dick's advice is crap. He'd said to just give you his card and let you go wild, and as iffy as that sounds, he's so desperate to make you happy that he doesn't care.
So, your birthday rolls around and he drives you up to the mall in his beat up Chevrolet truck. It's almost nonsensical how he has billions of dollars, yet that dark red truck is hanging on by a thread. After you've taken in the sights and mostly gotten used to the environment, he whips out his wallet like he's in a James Bond movie.
You - obviously - assume he's going to buy you one thing of your choice and that will be it. That would've been enough - he really didn't have to buy you anything at all. Then the fact that you're dealing with the son of a literal billionaire smacks you in the face as he gently places his black card in your hands and nudges you towards the stores.
At the confused look on your face, he seems bashful, for some reason. “Right. I forgot. Sorry, uh, The pin is four-eight-six-one.” After a moment when you still look confused, he adds “Just get whatever you want. It's on me. Well, mostly on Bruce, but it's on my card, so that counts, right? Happy birthday.”