During the "Mean Girls" portion of the video ... Ariana's "Burn Book" includes a page for Pete with the words "Sry I Dipped," "Love U Always" and "HUUUUUUGE."

Kris Jenner also made an appearance in the "Mean Girls" part of the vid ... playing Amy Poehler's "cool mom" character. As we first reported ... a Kardashian was gonna make a dancing cameo appearance. We didn't know who at first but later learned it was Kris, and the music video confirms it.

As you know ... the music video featured scenes from 4 female-driven films that have special meaning to Ariana -- "13 Going on 30," "Mean Girls," "Legally Blonde" and "Bring it On."

Tons of celebrities made cameos to help AG pull it all off ... including Jennifer Coolidge, Jonathan Bennett and Troye Sivan.

There's even a nod to Pete Davidson's nether regions ... Ariana has some dialogue with Coolidge where she mentions a boy with a "BIG" one ... she's dropped hints on Pete's genital size before.

Ariana's been teasing the video for some time now ... even releasing a behind-the-scenes teaser of the making of the music video. Fans and celebs alike were fired up for the video ... including Bella and Gigi Hadid.