Story: Joined a VoN 5 pug and it looked to be filling up okay. Then, we have a sorc join. He asks the party leader to invite his friend. The party leader went afk for a minute and when the guy got no immediate response, he said "Invite [insert name] or I'll drop". Now, if I had been the party leader, I would have booted him right there, but, as it happened, our party leader was feeling benevolent, and allowed him to stay. He even tried to invite the person in question. Turns out, they were in a party, in a dungeon. 5 minutes go by as we try to sort this guy out, and finally he gets into the group.
(Wait for it...)
The friend wasn't even flagged. I know right?
We boot him and fill. The Sorc remains and has a stunning performance of dieing 7 times, even though he's warned not to go down certain hallways etc etc etc.
Long story short: The guy spouted off at the mouth again and again and finally his stone ended up in Lava.
Moral of the Story: Don't be that guy. Don't threaten to drop party just because your friend can't come. IF you join and they don't take him, you can politely leave, but you are replaceable. Especially don't threaten to drop, have your friend turn out to be not flagged, and then be a constant burden on the party. There is no excuse for bad manners.