On Kikowani Station, you'll reach a point where the AI allies will mention something about a squid birthing chamber or some such silliness, and you'll see 4 Engineers ahead of you hovering above a platform and shielding each other. Just keep reloading this checkpoint and killing them until you get Naughty Naughty and Well... Maybe One or Two.
I've included a video below with loads of achievements. For these two achievements, start at
23:29.