Jack’s Mannequin started off as a side-project of Andrew McMahon, who is the vocalist, pianist and main songwriter of the band <a href="http://www.last.fm/music/Something+Corporate" class="bbcode_artist">Something Corporate</a> but has now become his main project. The band is based in Orange County, California. The name Jack’s Mannequin originated from one of McMahon’s songs called <a title="Jack's Mannequin &ndash; Dear Jack" href="http://www.last.fm/music/Jack%27s+Mannequin/_/Dear+Jack" class="bbcode_track">Dear Jack</a>, which was written about a friend of his whose brother was diagnosed with childhood leukemia. Andrew himself was diagnosed with leukemia on June 1, 2005 and cancelled a show for the first time ever when he received the call from his doctor.