Lady Gaga and Tony Bennett are not only collaborating in music, they also collaborated in art. Gaga, Bennett and renowned photographer Annie Leibovitz are auctioning off on Lady Is a Tramp for Bennett’s newest album. Gaga posed nude for both Bennett and Leibovitz during a Vanity Fair photo shoot for the January 2012 cover. While Leibovitz was taking the pictures, Bennett drew a charcoal sketch of Gaga.

The sketch is now up for auction and all proceeds will benefit Bennett’s non-profit organization Exploring the Arts (ETA) and also the Born This Way Foundation, Gaga’s non-profit foundation that focuses on anti-bullying issues, self-confidence and many more.

The auction already started and will end at Monday, December 19. The sketch is not the only thing being auctioned at http://celebrity.ebay.com/ and according to MTV.com, the list is as follows:

>>> The original portrait of Gaga by Bennett (18 in. by 24 in., charcoal on paper), signed by the jazz legend under his given name “Benedetto,” which he uses to sign his original artwork.

>>> Accessories Gaga wore during her Vanity Fair shoot, including Mercura sunglasses, House of Lavande earrings, an Alexis Bittar ring and a pair of Brian Atwood heels.

>>> Original print of Gaga’s cover photograph, autographed by Annie Leibovitz.

>>> A poster of the cover of Vanity Fair’s January 2012 issue, signed by Lady Gaga.

>>> A first-edition copy of the book “Lady Gaga x Terry Richardson,” featuring more than 350 photos of the “Born This Way” singer, with a limited-edition poster signed by both Gaga and Terry Richardson.

>>> A personalized autographed copy of the book “Tony Bennett in the Studio,” featuring images of Tony’s artwork and an exclusive CD.

>>> Limited-edition print of Bennett’s watercolor “Gondola, Venice.”

>>> Top-quality oil and acrylic brushes in a case signed by Bennett.

Which one will you get?