The state of a man's penis that is in-between the hard and soft state. During this time the penis is hard enough to defend the scrotum sac, but limp enough to dangle around. The male's hormones are just slightly aroused, causing only a minor increase in size. The reason for such a occurance is because the male probably did not finish his sexual thoughts or something of the sort. For example, he was interrupted half way through looking at an attractive female, or maybe he saw a woman that actually turned out to be a man, which forced him to stop having perverse thoughts.
Bob: "Im currently thinking about the hottest girl at school"
Bob's boss: "Hey kid get your head out of your ass. We have work to do"
Bob: "Well, my boss interrupted me halfway through getting a full erection, so I have a limp defender"