I'm a classic introvert: Hate crowds, am quiet around a group of strangers, like to come home and unwind after being out, I choose my words carefully and don't talk just for the sake of talking, etc. But after reading a lot about it and taking several tests, I realized I'm not 100%.
I've had extroverted GFs and sometimes that was tough. And one of my lunch buddies is a VERY annoying extrovert, but he's harmless. But what I tell him and others who know him, from his actions: He must think that negative attention is better than no attention. We can bash and trash him and he just glows because he's getting attention. And, it's better to blurt out something really stupid rather than just keeping his mouth shut because he does it all the time.
But it's not just extroversion. There's more going on than that. He's 79 but acts more like an undisciplined 4 year-old.