For a show that inspired a Change.org petition to have it canceled when it played downtown, the “Slave Play” that opened Sunday on Broadway delivers less a theatrical punch in the gut than a “Huh?”

The so-so show begins provocatively, with a trio of scenes depicting 19th-century mixed-race couples — slaves and masters among them — engaged in various sex acts. Using a silicone phallus and blatantly offensive stereotypes, these sequences are played broadly for laughs, and get some scattered giggles.

If chuckling at a black woman saying “Mas’r” while a white guy with a whip stands behind her isn’t your thing, “Slave Play” may not be your play.

The mood changes, though, as soon as the woman starts twerking to Rihanna’s “Work.” Granted, the song wasn’t the biggest Gramophone hit of 1850, but Jeremy O. Harris’ play has more devices than a RadioShack. Take the set: a wall of mirrors, revealing we the audience as the real main characters. Golf clap.

After one of the raunchy trysts goes haywire – spoiler alert! – an alarm sounds. “Starbucks!” someone cries, and we’re whisked to a modern room with folding chairs. Surprise: It was a therapy exercise all along! These are real couples, and now it’s time to unpack what just happened.

Harris’ format is undeniably clever, and it sets up what should be a series of dropped bombs about race, sex and love. But what drops is dramatic tension, as “Slave Play” fast dissolves into an academic essay.

The six participants sit down with two therapists, leaders of a hard-to-believe study called the “Antebellum Sexual Performance Therapy,” in which interracial couples with bedroom issues try to work them out via slavery role-play. “We read about this in the New Yorker,” one says.

The encounter isn’t pretty. The static white characters stubbornly channel Stephen Colbert’s “I don’t see color” bit, while the slightly-less-static black characters push back, ad infinitum.

Most moving is Phillip (Sullivan Jones), an African American man whose white lover and friends made him feel race-less. Most textured is Kaneisha (Joaquina Kalukango), who begins to wonder if her controlling British beau (Paul Alexander Nolan) should Brexit her life.

Some of the ideas are intriguing. Are mixed-race couples unable to separate their present-day romance from the horrors of slavery? And can their very attraction be rooted in oppression?

Yet, despite those hot-button topics, much of director Robert O’Hara’s production lags.

For starters, the Smith College jokes and Warby Parker types saying “I hear you” is a satire of liberals for liberals, and it doesn’t scorch so much as toast. Another problem is that many of the play’s forceful beliefs are lost in the cacophony of that endless therapy scene, which goes on breathlessly for about an hour. God forbid they include an intermission. When the default setting is “CHAOS,” it’s easy to tune out.

With all that time for development, most of the characters, such as they are, remain vague and archetypal. There’s little change from start to finish, and therefore no investment from us.

For better or worse, “Slave Play” is the sort of show you see to say you’ve seen it.