eating

To eat something up is to do it easily and well.  In the context of fashion that means pulling off a good look with amazing clothes and fabulous makeup.  So if someone appears in a stunning outfit you can compliment them by saying that they are eating it. From there eating moves to having an adjectival function so you can say that you are after an eating outfit.  While you could be interpreted as meaning ‘an outfit suitable for eating’, this would be wrong.  You mean ‘an outfit that is totally cool’.   And then you can say that your outfit is eating, although it would be better if others said it for you.