adverb. A phrase implying that you are dressed sharp, or stylishly; like a homosexual might dress - but still staying true to your gender. (not to be confused with cross dressing - which is to dress as the opposite gender)
Usually only applied to males.
eg 1: Since were all be gussied up, maybe we should go out for an expensive dinner too?
Dan: Look at you! You're all gussied up - What's the deal?
Stan: Joanne's bringing were hot flatmate Jessica, and she's worth getting all gussied up for.
Dan: I heard she was taken.
Stan: Really? Well I bet he doesn't look this good.