A Prom Dress
Prom is like a pre-wedding for teenage girls. There's food, drink, dancing and after-parties where … well, we won't go there. Also like weddings, it's not out of the ordinary for a well-to-do young lady to drop $1,000 or more on a dress she'll wear only once -- many of which look suspiciously nuptial-ready.
So, if you still have your prom dress and it's not out of style or too juvenile, slipping it on again for a formal affair might be awfully tempting, even if you're a decade or more out of high school. But you have to be careful, as there's a fine line between donning a vibrantly colored formal evening gown and a white, champagne or blush dress that'll make you look too much like a bride. Use discretion and err on the side of caution. If you're at all unsure, leave the flashy dress for the high school kids and wear something more elegant and adult.