Just tried to fix the tag name on Pureferret's question, Is Vaarsuvius male or female?, since the name of the webcomic is singular (Order of the Stick) and got an error message about "order-of-the-sticks" already existing:
Creating the new tag [order-of-the-stick] is not allowed since the tag [order-of-the-sticks] already exists. If you think this new tag should be allowed, raise it on meta.
Can it be renamed?