Chad Ironchest and Tuck Packerd are two muscular, attractive guys who appear in the Season 3 episode Cruisin'.
After Mordecai and Rigby watch a film where two guys pick up girls just by "cruising", Margaret and Eileen think that the movie is bias and inaccurate, and the conversation evolves into a bet between the four of them. If Mordecai and Rigby get a girl's phone number by cruising, then Margaret and Eileen have to buy dinner for them. If not, then they have to buy dinner for Margaret and Eileen (and later, their "dates" Chad "Ironchest" and Tuck Packerd).
They are both muscular guys. Chuck wears a blue hoodie and grey jeans, he has blonde hair and glasses. Chad wears a plain white top and brown trousers, he has black hair.