Third row from the bottom (http://www.screencap-paradise.com/caps/thumbnails.php?album=726&page=4), that's where the back fetish started. But there's two for the price of one (http://supernatural-caps.com/spncaps/displayimage.php?album=17&pos=89) and fully clothed (http://www.screencap-paradise.com/caps/albums/Series/Supernatural/SN_s1/SN103/thumb_Supernatural103_662.jpg). *melts*

Also, look at that face! (http://www.screencap-paradise.com/caps/albums/Series/Supernatural/SN_s1/SN103/thumb_Supernatural103_031.jpg)