Sex sells indeed.

Katy Perry performed at the amfAR Gala this week, benefiting AIDS research, and auctioned off a signed guitar for the cause... as well as a night at a gay bar and in bed!

E! Online reports that Perry sweetened the pot of an autographed guitar on auction by yelling, "I'll have sex with you, too!" As a result, Joe Francis of 'Girls Gone Wild' fame bid $10,000. Perry later offered to take the winning bidder for a night out at famed gay bar The Abbey. However, Francis wasn't the big winner. New York Giants owner Steve Tisch pledged $32,000 for the winning bid, at which point Perry hugged him and said, "I'm going to have sex with you." Keepin' it classy, Katy!

For her performance, Perry crooned her hits 'Wide Awake,' 'Firework' and a cover of Bonnie Raitt's 'Can't Make You Love Me.' Before launching into the cover tune, Perry said, "This song needs no introduction." Maybe John Mayer was on her mind!

It's the second cover she's performed at a benefit recently. The 'Hummingbird Heartbeat' singer also covered Al Green's 'Let's Stay Together' at a fundraiser for President Obama's reelection campaign. Is she turning into cover queen Kelly Clarkson?