8. Lily: Do you think he'll judge?
Serena: I think you should just sneak a peek at his little black book before you drop the yellow pages on him. Just make sure your numbers are on par.

sneak a peek: 偷看，peek本身就有偷看，窥视的意思。
black book: 黑名单，a book containing names of people or organizations to blacklist.
yellow pages: 黄页。这里Serena说Rufus的情人名单是“黑名单”，Lily的则是“黄页”，其实就是说Lily的情人太多了，名单厚的都赶得上黄页电话本了。
on par: equal to someone or something. 成正比，相抗衡。 Your effort is simply not on par with what's expected from you.

9. Rufus: It's just, well, I'm relieved...please don't take that the wrong way.
Lily: Oh, no.
Rufus: It's just you've dated more people than I have, and I wasn't sure that we'd be in the same ballpark.
Lily: Well, I'm glad that that is behind us.

don't take that the wrong way:不要误解了，不要想歪了
in the same ballpark: of a similar nature
I'm glad that that is behind us: 事情总算过去了

10. Dan: Spill it.
Vanessa: Spill what?
Dan: Come on, the minute we dropped Nate off, you just…you clammed up, and you got that look on your face.

spill it: 说吧，有话就说
drop somebody off: 放下某人，让某人下车
clam up: 拒不开口。clam是蚌的意思，clam up形容人的嘴巴像合上的蚌那样，关的紧紧的。

11. Serena: Why are we crashing Nate's family reunion? And why would Blair be here?
Chuck: Well, Dorota tipped me off. She's coming. Maybe she's ready to relaunch herself into blue blood society.

crash: 不请自来
tip somebody off: 泄漏消息
blue blood: 所谓的“蓝血贵族”，上流社会

12. Gossip Girl: The danger with calling someone's bluff is that even if you win...You risk them walking away from the table for good.

bluff: 打牌时候经常用，表示“虚张声势”，比如你手上的牌明明很差，但是你却下了很大的赌注，让别人觉得你拿了一手好牌。call someone's bluff就是不相信对方的bluff, 挑战对方或者提出看对方的牌，to challenge someone to give proof of his or her claims

13. Nate: Do you remember when you used to make us watch your favorite movies over and over again? Like "Tiffany's" and "Holiday"? It used to drive me nuts.
Blair: Is this a pep talk?

drive me nuts: drive me crazy, 让我抓狂
pep talk: 鼓舞士气的话

14. Dan: What? Why are you smiling?
Serena: I don't know. I am mad, but that was invigorating.

mad: 口语里一般指“生气”而不是“发疯”
invigorating: 爽快的，发泄的挺爽，这里S是说刚刚那一巴掌打的很泄愤。