Preppy is NOT obnoxious bright color combinations of fuschia pink with flourescent green, although pink and green can be a "preppy" combination if worn by women under 21. Pink and Green is Worth Avenue in Florida. Florida is not really preppy. Massachussets is preppy. Only infants and tourists wear pink in green in Nantucket.
Preppy is NOT spending the last dollar on an ill-fitting Lilly Pulitzer outfit that one buys simply because it's (a) Lilly Pulitzer and (b) pink & green.
Preppy is not over exposing yourself to UVA rays when you lay-out for 6 hours every weekend so that you go from white Anglo to African American. Preppies do get tan, but its from sailing or playing golf, and they wear sunscreen and get out of the sun if they can't keep some resemblance of WASP-ness.
Preppy is a term to describe a clean, conservative choice of dress with most apparel able to withstand years of wear and tear from sports such as sailing, golfing, riding horses and skiing. It is not cheap synthetic fibers in bright colors just because the designer occasionally produces preppy outfits.
Preppy is classic navy blue sweaters, sailor red pants, a hunter green car and crisp white oxfords. Preppy is not a strappy, body hugging fluorescent green with bugs embroidered on it dress with hot pink trim. That's just tacky.
The preppy girls from Miss Porters, who were home for vacation but still dressed with ribbons in their hair, white monogrammed oxfords, jeans and tretorns laughed at the public school townies from Darien when the the townie in the strapless pink and green Lilly Pulitzer top tripped in her fuschia Jack Rogers sandals. It was, afterall, thanksgiving and 40 degrees outside.