Why is Perry embarrassed to show his legs?

From the text:

Perry folded the map. He paid for the root beer and stood up. Sitting, he had seemed a more than normal-sized man, a powerful man, with the shoulders, the arms, the thick, crouching torso of a weight lifter, weight lifting was, in fact, his hobby. But some sections of him were not in proportion to others. His tiny feet, encased in short black boots with steel buckles, would have neatly fitted into a delicate lady's dancing slippers; when he stood up, he was no taller than a twelve-year-old child, and suddenly looked, strutting on stunted legs that seemed grotesquely inadequate to the grown-up bulk they supported, not like a well-built truck driver but like a retired jockey, overblown and muscle-bound, outside the drugstore, Perry stationed himself in the sun.