Chen verbally bitchslapping the fanatics who were willing to turn off the nuclear reactor on the Ark, especially if you failed the mission. "I SAID THREATEN TO DO IT, NOT ACTUALLY DO IT! WHO ORDERED THIS?! WHAT WERE YOU THINKING?!"
Finishing Security Day 3, because it is so difficult otherwise.
On a similar note, finishing Resistance Day 2. You will be yelling at Nechayev to hurry the hell up. Why you don't just have a heavy toss the wounded pilot onto his shoulders is beyond me.