Inspired by the same-day delivery answer, I remembered there's a service called "Magic" where you basically text them what you want and they quote a price:
We have trained operators standing by 24/7 to answer every one of your requests. Send us a text message, and we'll get you what you want. We'll order what you need from the appropriate service (e.g. DoorDash, Instacart, Postmates, etc.), and deal with them so you just automatically get what you want, like magic...
and from the FAQ:
Q: What kinds of things can I use Magic for?
Anything you want. As long as it's not illegal. Seriously. Just try it.
It might be useful if you have no money or credit cards as someone else could do it for you.
I've no idea if they're any good, I've always wanted to try it when I'm in the states but never have. I'm mostly posting because I think it would be awesome to ask a random service to find and deliver you underwear.