One fan even caught Blair and Gellar recreating their movie kiss at the event.
Witherspoon snapped a pic of the smiling trio for Instagram, writing: "Best girls night of the year!!! #cruelintentions."
The former co-stars met up to take in a performance of Cruel Intentions the Musical, a "completely unauthorized" parody featuring hits from the '90s and staged at LA's Rockwell Table + Stage, where they've done similar takes on Pretty in Pink and even Pulp Fiction.
Witherspoon also posted a photo from inside the performance, writing, "Sebastian and Kathryn reunite! #cruelintentionsmusical #90sflashback."
Meanwhile, Gellar was commemorating the day with pictures as well. She snapped an equally adorable group pic from inside the theater.
And the trio weren't content with just watching! Blair, Witherspoon and Gellar were both seen getting super into the show, and singing along to the musical.
Geller also posted a #TBT pic of her and Cruel Intentions writer/director Roger Kumble, wishing the filmmaker a happy birthday.
Blair also wished Kumble a happy birthday with a throwback pic, captioning: "#tbt To the day of #secretsociety dance on set of #cruelintentions. And a very happy birthday to the man who made that movie, one of my favorite people."
The only other main player from the '90s hit that didn't make it out wasSecrets and Lies star Ryan Phillippe
. However, he did make it out to a staging of Cruel Intentions the Musical
back in April, where he even showed off a sweet souvenir on Instagram.
This was also the second time watching the musical for Gellar, who attended a different show in April alongside her Cruel Intentions co-star
Sean Patrick Thomas. Gellar posted a video the next day with some of highlights from the production.
Gellar has been on a roll celebrating projects
from her past over these few weeks. Recently, the actress addressed the possibility of resurrecting her iconic vampire hunting valley girl character from Buffy the Vampire Slayer.