I've done this and once had a phone rep from Geico who was convinced I worked for them because my email was something like [email protected]. This was probably in the late 90s when email was still new to many people. She was really confused that I wasn't getting the employee discount. "Are you sure? Does a family member work for Geico? No? Are you sure?..." I don't think she ever did really understand what was going on.

Perhaps I could have saved even more than 15% if I'd just gone with it. :D