My Buddy Chips
From Halopedia, the Halo wiki
My Buddy Chips is an achievement in Halo: The Master Chief Collection. It is unlocked by encountering Chips Dubbo and listening to him speak in Halo: Combat Evolved. The achievement is worth 5 Gamerscore and can be unlocked on any difficulty.
The Aussie marine is first encountered on The Pillar of Autumn, and subsequently appears throughout the game. The achievement specifies that the player must "fight alongside" Chips, and so it will not unlock when he first escorts the unarmed player to the bridge.