What does Jordan means when she says, "And I like large parties. They're so intimate. At small parties there isn't any privacy"? What does it reveal about her character?
This comment of Jordan's also seems to support what Nick says about her, that "She [is] incurably dishonest." Jordan is someone who likes to control her environment, and this is probably because she is so dishonest. Nick recalls why he felt Jordan looked familiar at first: he initially recognized her from a near-scandal involving her alleged cheating in a golf tournament, an allegation that seems all the more true because it was hushed up so quickly when witnesses retracted their statements. At a large party, Jordan can blend in more; she can control to whom she speaks, and it would be easier to escape someone she might not want to end up in conversation with. At a small party, Jordan would likely be forced to speak with everyone present, and she would have a great deal less control over her conversation partners. Nick says that she avoids "clever, shrewd men," and this is likely because they are more apt to pick up on her lies. Further, "She wasn't able to endure being at a disadvantage," at which her loss of control in a small party would put her. Jordan's comments ultimately seem to confirm her dishonesty and her need to control her surroundings so that she can manipulate them as deftly as possible.
Although it sounds paradoxical, Jordan's statement does, in fact, make perfect sense!
Think about it this way--if you are in a room full of 100 people, and you are speaking to someone next to you, chances are that no one else in the room is listening in to your conversation--they can't! There would be too much noise and commotion and far too many distractions.
However, if you are at a small gathering of say 15 people, the chance that ALL guests are involved in conversation on one topic increases. Also, if you are engaged in a one-on-one conversation at this smaller party, the odds are greater that someone will overhear what's being said or that someone will come to your table and try to join in the conversation.
So, when Jordan says large parties are intimate, she means that large parties offer the opportunity for discussions in smaller groups that will not be overheard by all, whereas at a small party, everyone is aware of what everyone else is saying.
It's easier to get away unnoticed in a large crowd and spend time alone with someone than it would be if you were with a small group (everyone would notice you were gone right away).