My teen nieces would be, um, less than thrilled if their birthday present was a hundred bucks. I admit that for awhile I thought maybe their expectations were a bit high, but then I thought about my birthday cash presents from non-parent relatives when I was a teen, did the inflation math, and realized...nah, actually, they were right.
Nice to know it's very easy to do this stuff if you want to (I mean in practical terms, not endorsing the illegality).