Easy, just remove the vowels from the local part of the address: rndbrgr@example.com

Even easier: I have a list of pre-generated fantasy addresses on my smartphone and can pass one to randoburgerspot on the fly.

> fantasy addresses

Highly unrecommended if it's important or you're a repeat customer. It is easiest to pick a consistent generation scheme that helps you to remember the email address you gave. Obviously record it somewhere too (a folder for the first you've-just-signed-up email is easy)

For throwaway accounts it doesn't matter what you give.