Show Groups Under User Name
 

I've done this one one of my forums, but can't recall how it works...

Notice the group under the user name here:
http://www.railroadforums.com/forum/...324#post268324

It shows both "adminstrator" and then "Photo Critiques Welcome". The Critiques part is a publicly joinable user group, I know that much. But how do I get them to show up under the user name in the groups list? I set one up in another forum, joined it, but can't get it to show up...

I don't think this is a hack, but I can't recall how it's done?