Ass-to-Grass. A form of squat in lifting weights where one goes because deep possible. ATG (Anti-thymocyte globulin or AtgamÒ) is a medicine made use of restrict rejection in numerous types of transplantation, remedy for graft versus host condition and in particular clients with aplastic anemia. It will this by controlling your body's very own immunity system. It's offered as an injectable medication. ATG=Any Thing Goes. Usually said in conversation before a crazy particular date with somebody. All of that good shit abbreviation for 'at the fitness center' Aren't Tits Great?Use to praise a fantastic set of jugs.