That magical and poorly-understood state between a flaccid and fully erect penis. A jaybird exhibits a trademark curved and drooping demeanor. It typically occurs in the arousal phase during which the penis transitions from its common limp state of being to a full hard-on.
I was unsure about our first time together, but when I disrobed and she saw my glorious jaybird, the look in her eyes told me it was on.
I was rolling commando, as I always do. My jaybird got caught in my zipper. It hurt like hell.
a Deep South term from the 1960s and before which means approximately: fool, bastard, jerk, jackass, silly twit, silly billy, doofus, goofball, goof-off, layabout, delinquent, lazy bum, gadabout, joker, popinjay, etc. This word is almost always meant as an affectionate insult among friends, and doesn't carry much wallop. Cf. huckleberry and jackleg.
"You had all day long to mow the lawn and put on some clean clothes, son, and you haven't done a thing. You're such a jaybird." (said with a smile)