Hollywood, Calif. ? Animators Trey Parker and Matt Stone play it so close to the wire on “South Park” that even they begin to sweat.

“We treat this series like it’s live,” said Stone of the hit cartoon.

And sometimes, it almost is. Tweaking on the show has continued up until five hours before a broadcast, they said.

These days as “South Park” hits its fifth year on the air as of 9 p.m. Wednesday on Comedy Central the duo still keep the cable channel on edge every week.

It’s not how far the boundaries are pushed that worries the channel. It’s how close Parker and Stone come to not finishing an episode for the week because they can’t keep their hands off their creation for long.

“We don’t want to be structured in the way we work,” Stone said. “We are afraid if we are more structured and more corporate like … then it would start to feel that way.

“We want it to feel like two guys making a show from their basement.”

Parker and Stone were schoolmates when they met and clicked as animation collaborators.

The idea for “South Park” was born in 1995 from a video Christmas card titled “The Spirit of Christmas” for Fox television executive Brian Graden (now a master player of MTV).

The cartoon featured elementary school buddies Stan, Kyle, Cartman and Kenny as they watched a boxing match between Jesus and Santa Claus over the true meaning of Christmas.

Their video was the rage in underground Hollywood circuits and eventually caught the attention of TV network officials.

The two friends were in their mid-20s when they sold “South Park” to the all-comedy channel. It has grown from a cult phenomenon to an icon.

Stan, Cartman and Kyle have progressed to middle school. Last year, Parker and Stone really killed off Kenny after dozens of episodes in which he was fatally maimed just to return.

Each new death would spur the tagline: “Oh, my God! You killed Kenny!” Along with the stories of the boys, “South Park” also tells of the eccentric citizenry of a small town in Colorado, where Barbra Streisand has attacked in Godzilla fashion and an Ethiopian boy sought refuge from Sally Struthers.

The show has gotten as much attention for its biting social commentary as for its outrageous plots. Because episodes are done the week before airing, Parker and Stone can afford to be topical. They often make references to the current news.

Other episodes would rather just push buttons. One was about how many times a certain curse word could be used on commercial television (by the end of the 22-minute episode, the count was well more than 100).

“It’s a wide-open show. We learned early that we can focus on different characters and not to be tied to a few characters,” Stone said. “We think the show has improved, at least in the writing.”

Parker and Stone could easily hand off the franchise now to someone else. However, they prefer to keep doing it all themselves the crude animation, the voices and the scripts.

George Clooney, an early fan, lent his voice to play Stan’s gay dog. During a recent party to celebrate its five years, “South Park” drew stars including Coolio, Margaret Cho, Robert Evans and rock guitarist Slash.

Parker and Stone have created 94 episodes in five years. The new season will lead them up to episode No. 99.

So what will they do for the milestone? “We don’t know,” Stone said. “We don’t know what we’re doing next week.”