when your girlfriend takes 5 minutes longer at the store then she was supposed to and you go out looking for her and the guy you think she is with,, and you wake up in the middle of the night in a pool of your own sweat,, and someone has the machine you want to use at the gym and you would feel completely content murdering the person so that they never ever take your machine again ***8230; then you know the Tren is kicking in