Actors often make movies because they agree with the message behind them. That was not the case with the cast of "Reefer Madness: The Movie Musical."

"It says that if you smoke pot you'll kill old men, you'll commit suicide [by] jumping out of buildings," Neve Campbell said of the comedy, which debuted at the Sundance Film Festival in January, aired on Showtime in early April and will be available on DVD November 8. "It's hilarious 'cause it's so bad."

"You'll become a communist just from one toke," added Neve's brother and co-star, Christian Campbell. "I play the all-American boy who basically ... with one puff, suddenly becomes a crazed, sex-fiend, degraded human being."

"Reefer Madness: The Movie Musical," which also stars Kristen Bell and Alan Cumming, is the movie version of a musical that is actually based on a movie, the 1936 propaganda film "Reefer Madness" (also known as "Tell Your Children").

The anti-marijuana movie was intended to warn viewers against smoking pot at a time when it was still legal, but instead became a joke for decades to come.

"In the 1970s people would go to the theaters and smoke pot to watch it, because it was a lot better apparently when you smoked pot," said Christian, who starred in the musical for years.

"I was basically a 'Reefer Madness' groupie," said Neve, who plays Miss Poppy, the owner of the local five-and-dime store where teenagers indulge in milkshakes and dancing before experimenting in the reefer den. "I mean, I went to the play a ton in Los Angeles and New York. It's along the lines of 'Rocky Horror.' "

Although the movie's obvious message is hardly one either Campbell supports, the siblings believe if you read between the lines, the movie has something relevant to say.

"Politics right now has a very sort of fear-driven agenda to it, and 'Reefer Madness' was made to be a fear-driven idea as well," Christian explained. "The final lyric of our musical is, 'When danger's near, exploit their fear. The end will justify the means.' [And] that's happening today."

"The play kind of gives you an idea to yeah, question what you see in the news," Neve added.

Aside from "Reefer Madness," Neve has a few other movies in the can, including the romantic comedy "Relative Strangers," due some time next year.

"Ron Livingston and I are engaged, and he discovers a week before the wedding that he was adopted and decides to find his real parents," Neve explained. "Those parents are Danny DeVito and Kathy Bates, who are trailer trash from the South, and comedy ensues."

"Relative Strangers" was directed by Greg Glienna, best known for writing the first copy of the screenplay for "Meet the Parents" almost a decade before the movie was actually made.

Neve will also appear alongside Nick Nolte and Tim Roth in "The Death of Harry Tobin," an indie drama set on a remote Irish island where Campbell plays a witness to a murder confession 30 years prior.

"My character sends a letter to try and have [the murder] uncovered," the actress explained. "Tim Roth's character comes over from the mainland and that's how he gets involved in our culture."

Neve also has a few other movies in various stages of production, including "Partition" with Kristin Kreuk and "The Mermaids Singing" with Evan Rachel Wood, but said she hopes to follow in Christian's footsteps and do more theater.

Check out everything we've got on "Reefer Madness: The Movie Musical."

Visit Movies on MTV.com for more from Hollywood, including news, interviews, trailers and more.