What Are You Doing Step Bro? is a quote from a pornographic film which was later parodied in a series of TikTok videos.
The line is taken from the intro for the “Family Strokes” studio, which makes pornographic films based on a step-sibling sexual fetish. The line was parodied before hitting TikTok. For example, it was quoted in a video by Twitter user @Daric on July 27th, 2018 (shown below).
This is about as far as I made it into Outlast. pic.twitter.com/nRlTvNYxnY
— Daric (@Daric) July 28, 2018
On TikTok, the scene was parodied by user @EmilyRoseCollinz on December 12th, 2018, in a skit where she prepares for a serious audition, only to say the line (shown below).
The scene was then parodied as TikTok users took the audio and performed their own renditions of the scene. It was also parodied in numerous TikTok Duets (compilation shown below). An example by user @toesrdelicious was posted to /r/offensivememes.