Door: kelbytv.com/photoshopkillertips
Use the freeze tool to protect parts of the photo from liquify.
http://kelbytv.com/photoshopkillertips/2010/06/10/protect-parts-of-a-photo-when-using-liquify/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+PhotoshopKillerTips+%28Photoshop+Killer+Tips+%28Video%29%29