The people behind beloved children’s program “Sesame Street” have gone into Oscar the Grouch mode over the promotion for the upcoming Melissa McCarthy film “The Happytime Murders,” filing a lawsuit claiming that the film’s trailer “tarnishes” the Sesame brand.

And it’s quite the tarnishing indeed, according to the suit.

In the suit, filed in federal court in New York on Thursday, Sesame Workshop says that the promotion of the film makes unauthorized use of the Sesame Street mark with the tagline, “No Sesame. All Street” and a trailer featuring very un-“Sesame Street” themes.

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“Sesame seeks to enjoin Defendants’ deliberate effort to appropriate its SESAME STREET mark, and its trusted brand and goodwill, to promote their R-rated movie, The Happytime Murders, by way of a violent and sexually-explicit trailer. SESAME STREET is a registered trademark of Sesame, an organization with a long and storied history of ‘helping kids grow smarter, stronger and kinder,'” the suit, filed against STX Productions, reads. “Defendants’ widely-distributed marketing campaign features a just-released trailer with explicit, profane, drug-using, misogynistic, violent, copulating, and even ejaculating puppets, along with the tagline ‘NO SESAME. ALL STREET.’ Defendants do not own, control or have any right to use the SESAME STREET mark. Instead, they are distributing a trailer that deliberately confuses consumers into mistakenly believing that Sesame is associated with, has allowed, or has even endorsed or produced the movie and tarnishes Sesame’s brand.”

The suit goes on to state that the “threat of irreparable injury posed to Sesame’s mark and brand cannot be overstated. Sesame has worked for nearly 50 years to build, cultivate and maintain trust with its audience of parents and young children built on its reputation for wholesome educational programming. That trust, although built over a span of generations, is too easily lost and is now in jeopardy. Defendants threaten to inflict serious, irreparable damage to Sesame’s mark and brand by associating their adult movie with Sesame Street.”

The complaint goes on to allege that “a parade of social media posts, emails and public comments” indicates that the tagline “has confused and appalled viewers because of what they believe to be a serious breach of trust by Sesame by supporting this movie. Defendant’s actions have diluted and defiled Sesame’s beloved Sesame Street children’s television show and SESAME STREET mark by associating their trailer with Sesame Street.”

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In a statement to TheWrap on Friday, STX Entertainment’s representative in the matter, identified as “Fred, Esq.,” noted that STX worked closely with Jim Henson’s son Brian Henson — who directed “The Happytime Murders” — and the Jim Henson Company on the film.

He added, “we are confident in our legal position.”

“STX loved the idea of working closely with Brian Henson and the Jim Henson Company to tell the untold story of the active lives of Henson puppets when they’re not performing in front of children. Happytime Murders is the happy result of that collaboration and we’re incredibly pleased with the early reaction to the film and how well the trailer has been received by its intended audience,” said Fred. “While we’re disappointed that Sesame Street does not share in the fun, we are confident in our legal position. We look forward to introducing adult moviegoers to our adorably unapologetic characters this summer.”

In a statement provided to TheWrap on Friday, Sesame Workshop said that they “take no issue with the creative freedom of the filmmakers and their right to make and promote this movie, rather this is about how our name is being misused to market a film with which we have no association.”

“Sesame Workshop, the nonprofit organization behind Sesame Street, learned last Friday that the name Sesame Street is being used to market a graphic, adult-themed movie. We were surprised and disappointed that Sesame Street, a show dedicated to educating young children, is being exploited to market this R-rated film,” the statement reads. “We immediately contacted the film’s distributor, STX Films, and requested that they remove our name from the film’s marketing. They declined to do so. We take no issue with the creative freedom of the filmmakers and their right to make and promote this movie, rather this is about how our name is being misused to market a film with which we have no association. We regret that our fans and families have been confused by STX’s marketing campaign.”

The suit, which alleges trademark infringement and other counts, adds, “The promotion of The Happytime Murders should succeed or fail on its own merits, not on a cynical, unlawful attempt to deceive and confuse the public into associating it with the most celebrated children’s program in history.”

According to a description of the film, “The Happytime Murders” involves “the puppet cast of an ’80s children’s TV show” that “begins to get murdered one by one,” prompting “a disgraced LAPD detective-turned-private eye puppet” to take on the case.

Sesame Workshop is seeking a permanent injunction preventing the use of its marks in connection with the marketing of “The Happytime Murders,” as well as unspecified damages.

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TheWrap has reached out to a spokesperson for STX for comment on the suit.

Pamela Chelin contributed to this report.