Flesh Penis
In non-erect state, the so-called Flesh Penis (or "Shower") already is almost as big as in erect state. During erection, the erectile tissue in the penis does not grow substantially, but only thickens to assign the rigidity necessary of the penis for a penetration.
The popular opinion doesn't seem to be confirmed scientifically so far, that men with ancestors from hot regions of the world tend to the flesh penis, because there is no need of protection from the cold by the shrinking of the non-erect penis of blood.