Penis girth is the measure of how thick around your penis is. This is sometimes overlooked but is very important, especially to women. It just so happens that the first 1/3 of a woman's vagina feels the most sensation. Now you see why it's important to stimulate this area. But while most guys are worried about their size in terms of length, it is the girth that really makes their partner happy. But before I continue, let me clear up a common myth: any average vagina can be stretched to fit th.