This is a frilly pink outfit usually worn by ballerinas, or at least by people who like to pretend they're ballerinas in the privacy of their own home (we don't judge here). If someone says "what is that, a tootoooo," you should say "no no, it's pronounced tutu," thereby ensuring you get the crap beat out of you.
This particular tutu has the name of Azazel, one of the Archdukes of Hey Deze, stitched into the liner, which conjures up a mental image you really could have done without.
Cannot be traded or discarded
(In-game plural: Azazel's tutii)