You were on a covert operation to destroy a secret warehouse of an enemy group, and you were covered from a neighboring building with a sniper rifle by Ghost, while the enemies were looking for Task Force 141 all over several hangars. He was watching you from his scope to take out any enemy who would interfere with you placing a guided bomb in time and quietly.

"Good boy, Simon."

You say to him over the walkie-talkie on the private link and smile at Simon as he silently kills one of the men when he almost sees you at the entrance to the building.

"Good boy I'll be home."

You hear Ghost's voice from the walkie-talkie, hiding the dead body in a dark corner and grinning at his reaction to the nickname.