this first thing that comes to my mind at the mention of "preppy" is shirts buttoned all the way up, tucked into your pants, often times a sweater/cardigan, some nice loafers/boat shoes, and a big tote bag.

then again, that's how i would dress if i were told to go "preppy"

^ college kids in polyester pants? i think your definition of prep only apply to apiit students. lol