The Boeing 737 earned the nickname "Guppy" (specifically the "Baby Guppy" or "Fat Albert") because of its distinctively short, wide, and somewhat stout appearance compared to other narrow-body aircraft of its era. When the 737-100 and -200 series first debuted in the late 1960s, the fuselage was remarkably short—only about 94 feet long—while maintaining the same cabin width as the much larger Boeing 707 and 727. This gave the aircraft a "tubby" or "pudgy" silhouette that reminded pilots and ground crews of a small, round fish. The nickname was further solidified by the aircraft's low-to-the-ground profile, necessitated by its short landing gear designed for easier loading at smaller airports. Over the decades, as Boeing "stretched" the 737 into much longer versions like the -800 and the MAX 10, the "Guppy" moniker transitioned from a literal description of its shape to a term of endearment within the aviation community. Interestingly, the name is sometimes confused with the "Super Guppy," a massive, bulbous cargo plane used by NASA, but for the 737, it remains a classic piece of pilot slang.