She gussied up in her finest dress and jewelry for the special occasion.

Gorgeous Gussie Moran, US tennis player.

You might be allergic to an ingredient in them. Try not getting all gussied up like a harlot.

All gussied up and ready to paint the town red.

It means to get onto your finest clothing and go out on the town.

It refers to a quantity that can have any value you want. Or perhaps any value within certain limits.

It's basically "some stuff, we're not sure how much" gussied up in pretty language.