I’m not crying, you’re crying is a reference to a quote from the Starsky and Hutch movie.
The phrase is used as a humorous way for men to cover up their tears and their emotional vulnerability.
Starsky and Hutch was premiered on February 26th, 2004, directed by Tod Philips and featuring Ben Stiller and Owen Wilson.
“I’m not crying, you’re crying” has been the title of several songs since the release of the film, also appearing in YouTube videos.
The phrase would appear in Reddit threads starting in 2015, being often featured in memes, or discussions.
A clip of the scene was uploaded to YouTube by Owen Iverson on January 8th, 2019 and the expression was defined on Urban Dictionary in the same year.