Anyone thinking this is about pants falling down, pants too baggy you need to pull them up, needing a belt, etc. are scrubs.
Anyway, I still kinda have a habit of doing the "grab my pants at the knee between my thumb and index finger and tug just slightly just enough that a little sock is showing" before hitting a ledge trick. 100% nervous tick and fake steeze, but whatever I've been doing it since I was like 14 so my midwit brain has incorporated it into my skate life.