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Sometimes we forget that when celebs get all dressed up in their best (or in Mayer's case, his worst), that they're actually being charitable!

And last night's 5th Annual Keep a Child Alive Black Ball was no exception.

The event, which raised money for children living with AIDS, drew everyone from fashion, movies and music, including Jessica Alba, Justin Timberlake, David Bowie & Iman, John Mayer, Queen Latifah, Tyra Banks, Michelle Williams, Alicia Keys, Padma Lakshmi, Clive Davis and more!

Check out the monster gallery below!