I just tried the toilet paper tube test on my dick to see if I REALLY needed Magnums. No way does my dick fit in the tube! I can get the head in, but none of the shaft. That tube could be 1/4" bigger in diameter, and even then I'm not sure it'd fit.
So that's some good news, I just wish my cock was 3" longer both hard and soft, with a full coverage foreskin, maybe even with a little overhang.
