I use Postman for a lot of my API testing, including generating test data. For a long time I wished Postman would add faker to it's limited list of included JS libraries. Then I realized it was already there, but the documentation around it is just severely lacking.
The Postman docs has a variable list, but doesn't do a good job of explaining where they can be used. They work in the body or URL of a request, but not in a pre-request script or in a test.
To work around that, do something like this in a test or pre-request script: