Clearly, most of the people on this thread have permanent erections. If the blood ever rushed back out into the rest of their bodies, their veins would burst.
Perhaps, for that very reason, they never ALLOW themselves to become unaroused. Maybe they even avoid orgasms, simply edging 24 hours a day. Even while asleep - perhaps using toys or a friend?
...As for >>37617 though, where it's clearly flaccid (and one would think that bending it that way would be painful, even WHILE flaccid)... Yeah, I got nothin'.
Somebody else care to take a stab, or shall we just go with the usual "WRY U BRIN LOGIK 2 PR0N?"