Peyronie's disease is the result of inflammation and scarring in the erectile tissues of the penis, which leads to and abnormal curvature of the penis. Scarring causes areas of the penis to become less flexible. During an erection, the penis curves towards the area that can't stretch. Depending on the location of the scarring, the penis may also lose length.
Koro (medicine) - Wikipedia
Worries about having an adequate penis size is common. In one study, Penis size generally does not affect sexual function, but those who are less satisfied with their penis size report more sexual health problems. Those who are dissatisfied with their genital self-image are also more likely to feel uncomfortable to have others, including health care providers, look at their penis.
Penis size FAQ and bibliography
Sometimes, discussions about penis are associated with ridiculousness, and for some, it is considered socially unaccepted or taboo. On the other hand, penis length, girth, and function have been an issue for me. In modern society, penis size becomes one of the major cause of anxiety for men.
The first thing to say in answer to this question is that it doesn't really matter. More concern is usually expressed over the size of the erect penis. The size of the flaccid penis varies tremendously and depends on a lot of factors, and the environment is one of the most important.