Frasier: (to Daphne and Martin as he steps out onto his balcony) It's incredible! Dad, you should feel this -- it's eighty-degrees outside and it's the middle of February!
Moments later we learn that it is February 29th of a leap year, not quite the "middle" of February. Perhaps the line was supposed to be "the middle of winter", as Daphne states shortly thereafter.
Roz: His name is Gary. I don't know his last name. Anyway, we got to talking, and we were really connecting... I started to believe in kismet! And all of a sudden, all of these people wanted to get off the bus and I'm in their way, so I get off to let them out, and before I can get back on the damn bus drives off! Out of my life, forever!
Frasier: I'm sure another one would have come along in ten minutes or so.
Roz: I was talking about the guy.
Frasier: So am I!
Daphne: I love nature's little aberrations: warm days in winter, four leaf clovers, Australians...
Roz: What!? You're backing out after you made all of us take those stupid leaps.
Frasier: You bet I am! It may be an unwise man who doesn't learn from his own mistakes, but it's an absolute idiot that doesn't learn from other people's.
Niles: It's clearly an old wives tale because I'm still thinking of my old wife's tail.
Daphne: (to Niles) Would you like me to butter your buns for you, Dr. Crane?
Niles: You just don't want me to have sex because you're not having any.
Frasier: I most certainly am too. (wags his finger in Niles' face then he grabs it)
Niles: Your lips say yes but your cuticles speak volumes.
Niles: You don't realize how desperate I am. Ever since our seperation, I've been paying women to touch me.
Frasier: Oh Niles. (he feels sad for him)
Niles: Manicurists, pedicurists, facialists. Whenever you see a man who's well groomed, you can bet he's not gettin' any.
Martin: What the hell are you doing with him?
Frasier: I took him for a walk.
Martin: I was talking to Eddie.
(Martin talks about his harrowing plane trip)
Martin: Our landing gear's out, we're gonna have to do an emergency belly landing in six feet of foam! So, five hellish minutes later, we're bouncing across the runway. Then the stewardess comes out and says we're gonna have to go down the emergency slide. So down I go, headfirst into this sea of foam. Last thing I remember, this fat lady from across the aisle comes barreling down the chute after me like a polyester avalanche!
Frasier: My God, Dad, I am so sorry.
Niles: (horny) So, so, these stewardesses, were they also covered with foam?
(Niles is horny)
Niles: I need something to take my mind off the fact that at this very moment, Maris is slipping out of her frilly under-things and into a non-fat milk bath.
(Daphne enters with a hideous hairdo)
Niles: (horny, despairing) Oh, will these infernal temptations never end?!
(Daphne has a hideous hairdo)
Daphne: (sobbing, accusing Frasier) Take a leap! Mr. Maurice hair-designer! Trust me! Children pointing! Your fault!
Niles: I'm going to Maris'! (gulps down his sherry and flings the glass into Frasier's fireplace; it shatters)
Frasier: You will rue the day!
Niles: I don't care! Niles gotta have it! (leaves, slamming the door behind him)
Frasier: How long are you going to stay mad at me?
Roz: Until I get married.
Roz: (describing an experience she had while riding a bus) We were all crowded on there when suddenly I smell Lagerfeld and I... I look up and ... there he is.
Frasier: Karl Lagerfeld?
Roz: (after an exasperated pause) His name is Gary. I don't know his last name.
Karl Lagerfeld is widely recognized as one of the most influential fashion designers of the late 20th century -- "Lagerfeld" being a men's fragrance created by him. This exchange also explains the scene title, "NO, BUT I HEAR OLEG CASSINI TAKES THAT BUS". Cassini is an American fashion designer noted for being chosen by Jacqueline Kennedy to design her state wardrobe in the 1960's.
Frasier: You'll RUE the day...!
Frasier angrily snarls that to Niles, almost completely saying "You'll RUE the day you did that!" Frasier first spoke that line to Diane in the Cheers episode "Behind Every Great Man," and it sort of became his catchprase in that series. This was the first (and possibly the only) time Frasier ever used his catchphrase on Frasier.