A form of fashion fail, often causing the failer to resemble a crusty hooker from the bad side of Harlem. Most common in the preteen years, but can appear in the teenage demographic as well.
Remember, kids, there's a fine line between looking like Lady GaGa, and looking like a crack-addicted porn star.
Also can be used as an adjective, describing something that appears to be a serious attempt at fashion but has failed miserably.
Rebecca's choice of a pair of phallic pasties and a ripped-up miniskirt was pretty beautifail, especially since she's supposedly the best dresser of the 10th grade.