Why do guys with small dicks insist on showing them off? you have DEFINITELY seen a small dick right? when you see it and you think "well, that's smaller than I'd like to have" and you know he must know its small so why is he flashing it about?
Most guys have dicks, when you last saw one think back, was it big, small or average? chances are most of the dicks you have seen are small, at least smaller than average and this is because the guys with tiny dicks usually enjoy some degree of exhibitionism, whether they know it or not, they like small penis humiliation so the smaller guys are more likely to have had their dick out at some point in time, much more likely than the guy with the average size or larger dong.
What is small penis humiliation (lets trim that down to SPH)? well, it is a form of erotic stimulation whereby a man derives pleasure from being emasculated over the diminutive size of his penis. Lots of men enjoy this humiliation, sometimes even if they don't actually have a small penis but all men with small dicks enjoy it. Some women enjoy to deliver SPH as it gives them power, the men with the small dick enjoy it because it gives them a feeling of inferiority.
Societally, we are conditioned to believe that a big dick is a sign of enhanced masculinity, which it is and that a small dick is useless and only suitable for abuse and humiliation. Men with small dicks intrinsically know this and generally understand that this is the only form of attention their penis will receive and whether they appreciate the fact or not, deep down they know to expose it wherever possible, this is why when you see a naked man, there is a strong possibility that his dick will be smaller than average.
What constitutes a small dick? anything less than 9cm soft is pretty small though there is a strong chance that all the dicks you have seen were less than this as though to prove that smaller dicks are normally the exposed ones. Typically, studies show that anything less than 9cm is "small" but 7cm is not uncommon and 5cm or less would certainly classify as a small dick. Are there smaller? 5cm seems pretty little already? Well, the "short" answer is, yes. there are dicks less than 5cm and they can go as small as 0cm and have an inverted appearance.