Mimicking/practicing expressions

I used to always hear those like common experiences of people saying they’d practice expressions or talking or any facet of socializing in the mirror or something. And I always think “I don’t do that” but then I catch myself ALWAYS copying or expressing alongside YouTube vids or movies or shows. Like they’ll say something and I practice how I’d express it and I find it both really entertaining to do but also really funny that I even do it cuz like bro I would be so far behind socially (already pretty damn behind) if I didn’t do this ALL THE TIME