You're on a mission, making your way through a building with Ghost talking to you over the comms system. The whole night had been back and forth between him actually helping you, and him telling jokes.

As you're walking down a hallway, carefully clutching your gun and checking corners for enemies and loot, Ghost speaks up again. "Two goldfish are in a tank. One turns to the other and says... 'You know how to drive this thing?..' Little army humor." What a serious soldier he is...