The only shape that has no fruit connected to it is the hourglass shape.
Body parts like breasts can be compared to shapes too:
Melons (full and round), pear shaped (half full, most people have this), pointy (where the nipple sticks out), hangtits (hanging banana's), or flats (no tits)
Also may relate to a popular French Revolution caricature of "citizen King" Louis-Philippe, drawn by Honore Daumier and Charles Philipon in 1832 as a jowly pear. The French term "poire," or pear, was slang for "fool" or "idiot" - and soon thereafter, all caricatures of the King were banned, pear-shaped or not.