Yes, Rodney Mullen invented the kickflip (and damn near every other skate trick), but the reference here comes from a time when Tony Hawk would drive around and yell "do a kickflip" at skaters, if they did a kickflip he would sometimes give them a signed board or other things. Example video - https://www.youtube.com/watch?v=ob0dI05Xz8s - it became a thing for a little where people would yell "do a kickflip" at skaters they saw on the street.