In the episode "You Bette Your Life", Fran Fine was wearing an outfit consisting of a midriff-baring halter top, a skirt which looks like the lower half of a regular formal dress, and a boa.

http://www.fran-drescher.com/nannybilderhp/1/4.23fbette.jpg

Seriously, does this count as formal wear? I have never seen any formal gowns that expose her belly button, much less her midriff. What kind of formal gowns would do something like that, anyway?