For the most part.... this doesn't exist. It is not physically possible to go from small or 1.5 -2" soft to a 'massive' erection of 7 or more inches. The reason for this is because of the skins ability to only grow so much. This isn't a magic act. Even for girth the average growth is 2 time or less from flaccid to erect and for an flaccid to erect length it is generally 2 and MAYBE at the most 2.5 times it's normal length. Most guys go from like 3 to 5 or 4 to 6 or 7 or 6 - 8 or 5 - 8. Guys who go from 2 to 8 or 2 - 9" are lying as the body doesn't allow for it. I once heard someone exclaim that the had a 2" penis turn into a 10.5" and this is impossible, so I just laughed and walked away. Physiology dictates this and our penises are only so elastic to allow for such expansion in length and girth.
A lot of bulges come from the fact that the guy has larger testicles and scrotum and not just a large penis. When you factor in the large flaccid you create a bulge of nice proportions, and you can still have a decent bulge without the large scrotum and testes. A large flaccid will cause the pants or underwear to protrude as it drapes over the scrotum and hence-- creating that bulge that you are speaking about. Some men don't drape and point out instead as they have shorter flaccid penises of 2" or less, but then they are not huge when erect either. Those penises who drape over are more likely to expand larger and create that massive penis you are referring to in this thread. This is not to say that some men who are growers won't be showers, because they will, they just more than likely won't grow to 8 or more inches when erect.
I don't know of a case of a guy who is hung having no bulge or some sort. It makes little sense. There are those who are showers and only grow a little in length and girth or just get stiff, but they are generally hung and not of smaller proportions.
Hope that helps!