Size definitely matters. Ask your girl or guy if you can ram half a pencil inside them next time things are getting hot and heavy. They'll tell you to fuck off. Why? Because there would be NO sensation. It's an extreme example, but it proves the point. The vagina can only be stimulated if the nerves are actually being touched inside the vaginal canal. The thicker and longer the penis the more nerves and the deeper the sensation. Its simple anatomy. For the straight guy out there - I'll bet your ass hurts more when you take a big shit than when you have the runs, right? Same sensation for a woman.

Of course there are also all sorts of emotional attachments as well. A big dick = virility and strength. Women wouldn't be attracted to you if you didn't have disctinctly male characteristics. A big dick is about as masculine as it gets....I think we're splitting atoms once we get over 7 inches and 6 inches girth cause there are few women who will refuse that, but anything that is much smaller and you are at a serious disadvantage. For instance, I once used a big ass dildo on this chick. It was about 10 inches long and 7 thick. I fucked her right after and she was like "are you kidding me with that pencil" dick? My bigger than average dick was not satisfactory....

Size matters. It's only the small dudes and the overly nice women that tell you otherwise.