Update October 12: Paramount has since removed the Mean Girls (2004) movie from their official TikTok account, that had the movie in 23 parts, for free.
Paramount Pictures has uploaded the entire original 2004 Mean Girls movie that starred Lindsay Lohan, Rachel McAdams, Tina Fey, Lacey Chabert and Amanda Seyfried.
This is a surprising marketing stunt to celebrate and bring more relevance to the film once again, as well as to promote that there is a Mean Girls: The Musical movie releasing in cinemas, in January 2024.

Mean Girls: The Musical is going to be starring Angourie Rice, Auli’i Cravalho, Reneé Rapp, Jaquel Spivey, Avantika, Bebe Wood, Christopher Briney, Jenna Fischer, Busy Philipps, with Tina Fey, with Tim Meadows.
The entire 2004 movie has been uploaded in 23-parts for free, here on the official Mean Girls TikTok page.