Halsey

Corsetry, low-slung waistlines, cutouts, sheer dresses and outfits that are basically just straight-up lingerie were everywhere at the iHeartRadio Music Awards and 'Vanity Fair' Young Hollywood this week.

Plus, how Christopher John Rogers landed the "Gossip Girl" gig.

There will be seven (!) musical guests in total.

Stars took major hair and makeup risks on music's biggest night.

See all the crazy outfits from Beyoncé, Britney and more.