"Ariana Grande pulled this off because she's Ariana Grande," Bennett told ET's Keltie Knight on Friday. "I got a phone call on a Friday saying, 'Hey, do you want to be in Ariana Grande's new music video, 'Thank U, Next'? I was like, 'Why would you want me to be in her music video?' And they said, 'You're gonna be Aaron Samuels. She's doing Mean Girls,' and I was like, 'Oh, that's fun. Yeah, totally, I want to do that!'"
The actor said he was only on set for about four hours, and barely missed Kris Jenner's iconic cameo. It was another star, however, who Bennett thought he ran into while filming scenes in a high school hallway.
"Other than the height from the back, Ari looks just like Rachel [McAdams] from the back. Even from afar, when I saw her walking towards me dressed as Regina, I did a double take. I was like, 'They got Rachel to do this too?' And then I was like, 'Oh, that's Ari!'... I was literally in awe thinking that Rachel McAdams had shown up to set," he recalled. "And then she got closer, it was her. She nailed it."
While Grande brought her own spin to McAdams' Regina George, Bennett couldn't help but feel a little nostalgic for the old days.
"It brought me back. There was that moment when you're sitting in the chair, they do your hair and makeup like Aaron Samuels, and they spin you around for the first time and you look in the mirror. That was the first time I saw him in 15 years, and it was like seeing an old friend," he said. "It takes you back to that time when life was just simpler."
"I think that's why Ariana did this video... It's such a guilty pleasure video with all the craziness going on in the world, and especially all the craziness going on with Ariana the last couple months, this was something I think she needed for herself and for her fans," he continued. "Being on set with her shooting, it was very similar to the way it was when we were shooting Mean Girls, where it's just a bunch of kids. She reverted to a 16-year-old girl again, and was just... so full of life on set."
Bennett, who also sat down with ET Live, couldn't stop gushing about Grande's work ethic. "When you're working with her on set, she just... she brings that out in everyone, she wants to make sure that everyone is taken care of. It's very rare," he shared. "Ariana is one of the best. She's hands down one of the most gracious, beautiful people you'll work with."
While he lent a few hours to Grande for "Thank U, Next," Bennett has quite a lot on his plate these days. He recently released The Burn Cookbook, his own tribute to Mean Girls in cookbook form.
"It's another way for fans to get together, watch the movie, relive some of their favorite moments, make food with their girlfriends and just have a laugh and a good time, which is what we need in the world right now," he explained, before teasing his new holiday film, Christmas Made to Order.
"Christmas Made to Order is by far my favorite Hallmark movie that I have done so far," he said of the film, premiering Dec. 23 and starring Alexa PenaVega. "It's about a girl who decorates places for Christmas... she teaches me the true meaning of Christmas and love."