shes just saying that to keep you happy , scientific testing  has proved otherwise , in a recent study women were shown computer generated imagines of men with varying size of equipment and nearly all the women chose the guy with the big cock lol

scientists  think this maybe why humans have  evolved with relatively large penises compared with other primates etc

https://www.google.co.th/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=women%20prefer%20men%20with%20larger%20penises