fun has 18 questions, 17 of which are closed and one of which is locked. Many of the closures may or may not be directly attributable to a certain flag-frenzied feline.
Really, I can't think of any legitimate question nowadays that would be tagged as fun. It's not a tag that people would watch nor is it one with predictable content. Not to mention, it has nothing to do with Systems Administration (unless simultaneously paired with cricket-bats and/or mysterious-reproducible-ground-faults).
As Iain points out, there are 16 people watching this tag. I saw that when I first perused it, but figured that they were relics of a bygone era. Back in the elder days, when crazy questions like "What is your favorite server naming scheme?" and "What is your worst SysAdmin horror story" were allowed to roam the streets unchecked, the fun was probably a pretty kewl tag to follow. I like to think that that's where the current followers come from and that there's no merit in the follower count anymore.