Well... Maybe One or Two
From Halopedia, the Halo wiki
Well... Maybe One or Two
Well...Maybe One or Two is an achievement in Halo: The Master Chief Collection. This achievement is obtained when a player kills 25 Engineers in Halo 3: ODST or Halo: Reach
Trivia
The name of the achievement is a reference to Buck's line in Data Hive, after Dare explains that the Engineers are harmless and asks if he's killed any.