I'll say what we are all thinking...
The size of a mans penis effects his self esteem more than it affects his actual sexual abilities. Men with small penises, or who believe they have small penises generally are shyier sexually, and around other guys. They don't like to talk about it, or will lie.
Now, that of course is total BS. I am either average for a white male or undersized, I don't know, depends on where your average comes from. And frankly, I could really care less. I am probably one of the few guys that would say NO to an extra inch or two.
Reason? As the phrase used above "There is a key to every lock" My key is just the right size for my mates lock, and an added inch would be... uncomfortable.
That being my reasoning for my thinking, I shall now end this X-rated spout of gibberish, with a final little quip.
SIZE DOES NOT MATTER. It is what you do with it that counts! No women really (Going on a limb here, I lack ovaries) wants the trousersnake some men claim to sport that would make a horse blush. That is just WRONG.