The cartoon character, Popeye, has "ham-hock forearms."
A ham-hock is a cut of meat from a pig. (The meat of a pig is called "ham" or "pork.") The hock is a part of the hind leg. It is very muscular and thick. "Ham-hock forearms" means that his forearms--the part between the elbow and the hands--are very muscular, so muscular that their shape looks like the shape of a ham-hock.
It means his forearms are very muscular. It means that he has great upper-arm strength. It suggests that his forearms are even more muscular than the ideal for male beauty.