Kanye West paid a favor to artist George Condo on Saturday by performing at his daughter’s sweet 16 party for free. Condo designed the controversial album cover art for West’s latest album, “My Beautiful Dark Twisted Fantasy.” (West said on Twitter that one image of him straddled by a naked woman with wings was banned by some stores.) The “Runaway” rapper performed a 30-minute set on the third floor of the Standard Hotel. The teen’s friend said West’s cameo made the night “the best of their lives.” West later showed up at club Avenue at about 2 a.m. with Kid Cudi, and listened to DJ Sam French play tracks from West’s new album.