Parker Posey on Her Wild 'Beau Is Afraid' Sex Scene: 'No One Would Do This — and No One Could' (Exclusive)

"I think the movie has a lot of poetry to it, and it's just very effective," Parker Posey tells PEOPLE of Beau Is Afraid

Parker Posey's appearance in her latest film Beau Is Afraid is brief but jaw-dropping.

In the film, from Hereditary writer/director Ari Aster, the actress shares a boundary-pushing sex scene with Joaquin Phoenix. The unpredictable comedic thriller, which Posey likens to PEOPLE as "an amusement park ride," follows Beau (Phoenix) on a psychedelic journey to connect with his overbearing mother, played by Patti LuPone. Posey, 54, plays Beau's former love interest from his teenage years who comes back into his life.

"I think the movie has a lot of poetry to it, and it's just very effective," Posey tells PEOPLE in this week's issue. "I don't know why certain images stay with me, but I can meditate on them and go like, 'Oh yeah, that's in my psyche. That's in my universe.' "

Related:Joaquin Phoenix Undertakes an Epic Adventure in First Trailer for New Movie 'Beau Is Afraid'

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

As for her intimate sequence with Phoenix, Posey proudly says, "No one [else] would do this, and no one could do this. My career, my path, is of the unexpected. I don't know how to explain it other than it was a deep experience for me."

She also loved the opportunity to share scenes with Broadway legend LuPone. "The first time I'm meeting her, she's standing on a balcony in a bathrobe, waving her hands like Evita," Posey marvels, referencing LuPone's Tony-winning Broadway role. "I just loved being in her presence."

"There such magic to the story," says Posey of Beau Is Afraid. " It works on such a deep and funny level, and it's emotional."

Despite the film's dark themes, Posey says "we laughed a lot" on set. Comparing Aster and Phoenix (who she previously starred with in Woody Allen's 2015 comedy Irrational Man) to "great surfers," Posey praises Phoenix as "so fluid." "Without sounding too woo-woo, it's like the waters that they create together, you just go in and you get on the surfboard and you go. And it's great because you don't really have any decisions except to be there because they're such professionals and they're so artful that, you know you can trust them."

Beau Is Afraid is now playing in theaters.

For more about Posey, pick up this week's issue of PEOPLE.

For more People news, make sure to sign up for our newsletter!

Read the original article on People.