my kid and the lawn mower

so my teenager is supposed to cut the grass every weekend but he always makes excuses so this last week i get frustrated bc it's like a jungle back there already, we need rain or something. anyway i catch him playing video games again on saturday when hes supposed to be working on his car project from school and i snap. i take my lawn mower out, set it for super short and go to town with it in the front yard first. next thing i know he's coming outside like what is happening but i dont care, i keep mowing until its all done and neat as a pin, then leave him standing there shocked. then later that night i hear him out back trying to fix stuff up himself and thinking id never notice if the grass was long or short. well of course i notice! so when hes like dad why did u do this? i just say its payback for not doing ur chores on time, deal with it. hes still mad at me but honestly i dont care much now that its done right.