When doing standing doggy style with a longer than average cock if you stand up straight while getting fucked from behind you can usually find your G-spot as the cock will rub along the top (or "ceiling") of your vagina. I found mine many times. Usually with a guy who has 8" or more.
a Jumbo60606 :Benefits of a big cock .. glad you said 8 inches plus .. many of us guys try positions we are not equipped for .. women know whether it's working or not .. thanks for confirming