This person--typically female--has been on a study abroad and, if given the chance, will tell you every last detail about it. After anywhere from two minutes to four hours, you will feel as though you too met the BEST people and lived in the BEST city and ate the BEST food and found the BEST hidden markets and strolled through the BEST parks...but she will regretfully inform you that you could actually never understand. It doesn't matter how long she's been home; every single factoid and memory about her trip is as fresh in her mind as if she came back to America that very morning. She left the States a mediocre dresser and returned from her time abroad an imposing fashionista, compulsively adding scarves, boots, weird jewelry, obnoxiously-colored tights, etc. to her wardrobe. The number one defining feature of the DC, however, is the International Study Program backpack. Scientists are currently hard at work to determine which color of these backpacks is most common: green/gray*, blue/darker blue, red/orange, or yellow/gray. If you spot the little globe on the outermost pocket, casually mention different European cities while speaking to her until her eyes either widen excitedly or glisten with nostalgic tears.
*this is the one I have [insert winky face emoticon]