The cast of Cruel Intentions the Musical, running Thursdays and Fridays at the Rockwell Table and Stage in Los Angeles, talked to ET about having the original cast drop in for a performance of their "completely unauthorized" parody.
Reese Witherspoon, Selma Blair and Sarah Michelle Gellar partied like it was 1999 on Thursday for an epic Cruel Intentions reunion as they sang along with the actors portraying the characters they made famous 16 years ago.
"They were freaking out about seeing the show as we were freaking out about them being there," actress Emma Hunton told ET.
Molly McCook plays Witherspoon's character, Annette, in the production and she told ET that the Oscar winner actually chimed in during the live show.
"It was surreal," she said. "Reese said one of my lines with me. She felt it in the moment and she said it and it almost threw me off because it was so unbelievable."
And the fun didn't stop there. The ladies turned into fangirls, snapping pics to remember the moment.
"They were taking selfies with characters behind them," said John Krause, who plays Ryan Phillippe's character Sebastian. "They would take a selfie with us in the background. It was unbelievable."
This was the second time Gellar had seen the musical, as she attended a show in April alongside Cruel Intentions co-star Sean Patrick Thomas. She posted a video from her first visit in an Instagram post below.