Bustle, Bustle, who's got the Bustle

I looked it up on ebay...I looked it up on etsy. I still don't know what a bustle really is. I was told I need one from the "experts" at David's Bridal. I brang my dress home and they didn't even offer to show me a bustle or to try it on with my dress. They just talked amongst themselves about how I need a bustle. Now I am home wondering what in the devil is a bustle. Ebay had something that looked like one of those neck pillows. Etsy had bustles that looked like stripper's lingerie. I still don't know what I am talking about and if that is really what I need or is it something else entirely that would work better. My dress needs something definitely since it needs to poof. I have "pick-ups"...it's actually more of a pinch really all over the bottom portion of my dress, like cinderella. It doesn't pop-up quite like Alice in Wonderland's dress did when falling down the rabbit hole. I think I may need a bustle....help!