LMAO I'm sure that sounded great in your head, but if that service was actually worth 10mm, both parties would have to pay taxes on that income when they report it to the gov't for inclusion in GDP. Yes this applies even if no money changed hands: https://www.irs.gov/taxtopics/tc420

And yes there are workarounds, but clearly it's not that easy to manipulate GDP. If anything, you want to underreport these numbers so you don't owe as much.