Ground Control

From Ground Control 1, towards the end of the Order campaign:
Jared Stone: "If Hayes and Aegiri succeed in activating the polar Xenofacts, they will unleash a plague of death and fire across this entire section of the galaxy!"
Sarah Parker: *wolf whistles* "You sure are a charmer. A simple 'we'll be screwed' would have done it."
- In General, Parker shows herself to be a master of snark.

Ground Control 2

The very first cinematic in campaign mode sees an NSA soldier caught admiring a woman lingerie shop when CSS Astrid's beacon landed on him.
In Viron campaign of Ground Control 2, Angelus spends time commanding Virons. Then Drahk'Mar jokes that he might have the honor of commanding human troops in the future.
- It's even funnier considering that in the NSA mission "Push", you can actually give him your units to command.
The NSA dropship in Ground Control II, statistically one of the more stronger unit in the game when fully upgraded, boast some funny lines.
NSA Dropship: (Returning to base) "Copy that. Later losers."
From the 11th mission where you need to rescue Dr. Alice McNeal from the Terran captivity, General Warhurst's rant when he busts Angelus is priceless.
Warhurst: "CAPTAIN!! What the HELL do you think you are doing?!"
Angelus: "We're having a bloody picnic, general."
Warhurst: "Dammit, Angelus! You better survive this, as I will personally break one bone in your body for every piece of NSA equipment you lose out there! Warhurst! Out!!"
Alice: (After Warhurst finishes his rant) "In a bit of a snit, wasn't he?"