Everybody laughs. Nobody thinks that's weird or dumb. It is both.
Ivy: "Hey, did we make that person jealous?"
Nate: "I don't even remember what you're talking about."
Ivy: "Let's kiss!"
Diana: "We are going to be different from Gossip Girl and other anonymous sites, which traffic in damaging rumors and innuendo... Some girl kissing my teenage boyfriend... Sorry, where was I? Um, the Spectator is only going to print facts. If you did it, you deserve to get caught! And we're gonna catch you! So with apologies to my other esteemed editors, starting tonight, I'm gonna be poaching your best reporters and stealing all your best stories. And bombing you! I have schemes on everybody all the time!"
Things get even more ludicrous.
Chuck: "I have a story for you! My therapist, Dr. Eliza Barnes, has been using hypnosis to coerce me into performing unspeakable acts!"
WHAT? That's amazing. Let's stick with that.
...Or just pretend he didn't say it, for some reason.
Barnes: "My name is Dr. Elizabeth Barnes, and I did not hypnotize Chuck Bass."
Diana: "That's cool, but why are you at my party?"
Chuck: "Okay, she didn't hypnotize me into doing unspeakable acts. I don't know why I said that. But she did take money from a guy at a dog park."
Diana, verbatim: "Now that's a story I can print!"
Blair, out of nowhere: "Chuck, stop accusing people of things! You must be trying to ruin my marriage or something." Chuck: "Yes, it's both. Your fiancé was the one paying her!"
Gossip Girl: "Don't worry, B. You're still marrying a prince... Of fools!"
I defy you to explain why or even how any of that mess went down. What a bullshit turn of events. It's like, if you explained to somebody about Georgina Sparks and why that was good, maybe you could end up with Juliet. And if you explained Juliet but forgot to explain why it was pretty good, then you would end up with Diana Payne the Human Plot Device, just running around throwing parties and being weird and Chuck yelling random shit about how he got hypnotized.
Blair's point is that Louis should not have been arguing with her about her scheming proclivities, although technically he never did, but it was hypocritical of him to then turn around and scheme about Chuck. Louis's point is that he found the paternity test that proves she cheated on him. Louis wins.