About 17 years ago, a Secret Board of Shadowy Figures had a bunch of dead historical figures unearthed and cloned. The clones were all brought to term, raised by foster parents and sent to school. Today, they're all seniors in high school under the supervision of Principal Cinnamon J. Scudworth and Vice Principle Mr. Butlertron, Scudworth's robotic butler.
Though an entire class worth of the clones of world leaders, military commanders, great thinkers, inventors and, for some reason, celebrities, attends Clone High, the central cast is Abe Lincoln, his best friends Mahatma Ghandi and Joan of Arc (who is infatuated with Abe), and the popular kids, Cleopatra and JFK.
Clone High is largely a parody of the teen drama shows; every episode is referred to by the narrator as a "very special episode," charicatures of standard teenage issues like underage drinking, love triangles, or the percieved importance of prom, and... I'm sure there's other stuff; I don't really watch teen drama. There's heavy use of weepy music in the soundtrack which I'm told is "emo," whatever that means.
This show is aggressively stupid, but in a good way. I'm a particular fan of Scudworth, who is established right off the bat as a complete loon, and Mr. Butlertron, who was programmed by Scudworth to emulate Mr. Belvedere, including addressing everyone as "Wesley."
A number of people I know who've been exposed to the show didn't really care for it but grew to like it, and I think I've pinpointed the exact joke that changes their minds: in the episode "Film Fest: Tears of a Clone," it's established that Joan of Arc makes art films when the Clone High Film Festival is proposed. As the students make their films, we watch as she puts the truth into hers, as encouraged by Abe. At the Festival, we watch The Truth Wears Sideburns; un filme du Joan of Arc, a purely nonsensical parody of college art films and German Expressionism. At the end of it, the entire audience gives a collective "Huh," except for a little bald bearded character we've never seen before who's next to Joan, doing a little dance as the following exchange takes place.
Unknown character, singing to the "Nanny-nanny-boo-boo" melody: Ha ha ha ha ha ha, you lo-ove Abe! (Stops singing) Could it be any more obvious?
Joan: Go away, Sigmund Freud.
Freud continues taunting Joan for a moment until she hits him with a folding chair.
That joke summed up the series better than anything I could find; clearly smart people telling extremely stupid jokes. If you buy the DVD (which you really can only do if you live in Canada for the moment), watch this episode first. Don't worry, there's no real continuity to speak of.
It's also noteworthy that a handful of performers I consider unfunny most of the time are actually quite funny on this show. Andy Dick, who really had no business making fun of how over-the-top Tom Green is, does the voices for several minor characters, some of which is quite funny. Speaking of Tom Green, he had a guest appearance in the episode "A.D.D.: The Second 'D' is for 'Disorder'" that was an odd bit of self-parody and a clever bit of comedy. MadTV alum Michael McDonald provides the voice of Ghandi and not only gets some of the best lines in the series but actually delivers his lines with far more skill and timing than I've ever seen from him.
I really can't say much more, as the show's style is a little too varied to describe; the source of the comedy isn't drawn from the characters' genetic parentage as often as the show's title might lead one to believe (aside from the occasional line like "I'm the genetic clone of Abraham Lincoln; I'm not fit to be president," and "If there's one thing Mahatma Ghandi stands for, it's revenge!") nor is it even drawn primarily from the teen dramas the show relentlessly parodies. The style is too sporadic to really explain without giving a review of each episode, which isn't practical. All I'll say is; if you get the chance to watch the show, keep an open mind and don't rule the show out because you think its humour is juvenile or stupid. You'll have more fun that way.