With Hide Legs now freeing up people to more commonly show off the default undergarments, a new selection of color options may be prudent.
But why stop there? Using the guild tabard information, tasteful undergarments could also be created. The primary color of the guild tabard could also become the new main undergarment color. The secondary color could be used as a border. And the crest could be put up on each cheek.
I've mocked up an example here:
I personally don't think I'd rock this too often, but my guildies might appreciate the option.