OK. So buy something with Bitcoin without:

* Ever appearing at a retail establishment with security cameras

* Ever scheduling a product for delivery to any address, period

* Ever scheduling a service to be provided at any location, period

* Ever communicating with the other party via any means whatsoever, including placing an order online, not even via Tor behind seven proxies

And tell me how it goes. Because all of those things above are vectors for identifying you that big random numbers won't solve.