Don't bother to look for it on distrowatch.com - it's not there (at least it's not on the top 100 list sidebar on the right of the page). I actually can't remember how I heard about this one. It was probably in an article with a name like "top ten oddball linux distros". But it does exist.
If you do a search or two, you can still find Hannah Montana Linux.
I'll not bother to link to the download mirrors, since the Kubuntu base system appears to date from the kid's show character in its title, which would be around ten years ago. Running apt-get didn't locate much of the guts, so the thing isn't quite supported these days. Anyway, other than a garishly-colored installer, its main feature appears to be desktop wallpaper in purples and yellows.
This blast from somebody's past inspired me to look up some things that are still (kind of) around:
jihad.net - the game lampooning some "Barney" character that used to drive parents to the brink of sanity
hamsterdance.com - those dancing critters that we discovered when the 'net was new
wakeuplaughing.com - here's Steve Baherman's character Swami Beyondananda... religion jokes R us.
plan9 - Introducing Plan 9! The only OS named after an Edward D. Wood film that must have cost all of $300 to shoot
Intercal Programming Language - a joke that actually compiles... sort of
old "Conspiracy Theory" film promo page - at the link tab marked "???" there's a theory generator form that doesn't really work anymore, but somebody could probably figure out how to move it to a working location. Much funnier than the film (which sort of had its moments).