Discord has them. Now your cool Blizzard Group can have them too!
This addon lets you set nicknames via member notes. To add one, type "[name] Your Sweet Nickname" in the member note (be sure to replace Your Sweet Nickname with the one you so desire for yourself or someone else), and the addon will pick it up instantly and show it instead of their ugly name.
DISCLAIMER: Other people need this cool addon too if they want to see the nicknames.