"Natty" means natural, and describes those who lift without performance enhancing drugs such as steroids, although some questionable supplements might be allowed. The opposite, describing those who use such drugs, might be "enhanced".
Creatine will let you push an 8 rep set to 9 or 10. And when every pound on the bar is bought with two weeks of complicated periodization, that little bit helps. And creatine is allowed by basically every athletic league.
Real PEDs are a whole different ball game. Much bigger risks.