Answer by taking a quote from the following article:

Jackass is an American reality series, originally shown on MTV from 2000 to 2002, featuring people performing various dangerous, crude, self-injuring stunts and pranks. The show served as a launchpad for the television and acting careers of Johnny Knoxville, Bam Margera, and Steve-O, who previously had only minor acting roles. The show later sparked several spin-offs including Wildboyz, Viva La Bam, Homewrecker, Bam's Unholy Union, and Dr. Steve-O as well as three feature films distributed by MTV corporate sibling Paramount Pictures. Jackass sparked considerable amounts of controversy, as it was seen as indecent and encouraging of dangerous behavior.

Since the first episode, Jackass frequently featured warnings and disclaimers noting that the stunts performed were dangerous and should not be imitated, and that recordings of any stunts would not be aired on MTV. Such warnings not only appeared before and after each program and after each commercial break, but also in a "crawl" that ran along the bottom of the screen during some especially risky stunts, as well as showing their "skull and crutches" logo at the bottom right of the screen to symbolize the stunt performed as risky. Nevertheless, the program has been blamed for a number of deaths and injuries involving teens and children recreating the stunts. Connecticut Senator Joe Lieberman followed up with a February 7, 2001 letter to MTV's parent company Viacom urging the company to take greater responsibility for its programming and do more to help parents protect their children. MTV responded to the criticism by canceling all airings of Jackass before 10 p.m., but Lieberman's continual campaign against the show led to MTV refusing to air repeats of the later episodes, a move which angered the cast and production crew of the series who were furious with MTV's "caving into Lieberman's demands". A man named Jack Ass sued MTV for $10 million, claiming the series was plagiarizing his name. Jack Ass, formerly known as Bob Craft, changed his name in 1997 to raise awareness for drunk driving, after his brother and friend were killed in a vehicle accident. Matt-Dillion Shannon, an 18-year-old from Napier, New Zealand, was sentenced on November 23, 2012 to three years in prison on a charge of causing grievous bodily harm for his role in the August 2011 dousing of a 16-year-old with gasoline and setting him alight. Shannon's lawyer claimed that this act was inspired by the Jackass series, despite the fact that no such stunt ever aired on the show.

Did people have to be warned about the show?
Jackass frequently featured warnings