A good deal of the banter between Kasumi and Garrus is hilarious. One of the highlights is on Tuchanka after the events at the Hollow.
Kasumi: "You look entirely too satisfied with yourself."
Garrus: "Not every day I get to act it up like some over muscled vid-star, Kasumi. Let me bask in it for a minute. Where were you anyways? Didn't feel like joining the universe's most bizarre krogan krantt?"
Kasumi: "You know better than that. The spotlight isn't for me. Best, not most famous, remember?"
Tali gets Garrus to talk about his budding relationship with Kasumi by threatening to flood his omni-tool with elcor porn and Krogan opera if he doesn't. Garrus even notes that she's using his C-Sec interrogation tactics on him.
When the rachni show up on the Citadel (after having saved it, for that matter) the populace reacts... poorly. One woman tries to climb a turian C-Sec officer "Like a very stoic tree" while a volus topples over and is unable to right itself.
EDI and Shepard having The Talk while one of the Rachni warriors is nearby.
Shepard: "I'm not a great person to be asking for love advice, EDI."
EDI: "The concept of romance and sexuality is mostly restricted to organics. There are only two sapient organics in this elevator."
Numerous confused glances, alien and human, turned in the thief's direction but she merely rolled her eyes.
Kasumi: "Nevermind. I'm not explaining cartoons to an evolved velociraptor, two giant bugs, and the rest of you."
Javik's reaction to the husk head in Bryson's lab:
Javik: "I have seen worlds burn and millions die, but I still find myself mildly disturbed."
The assault on Omega consists of Aria T'loak, Miranda, Jack, Zaeed... and Carmichael, an Unlucky Everydude who just happened to be the pilot of the shuttle that brought said team to Omega. The guy tries, but he just can't keep up with the rest of the ultra-badasses in his group. He can only lament his bad luck after they are saved from Adjutants by Nyreen's Talons.