You were working undercover and told by Price that Ghost and Soap would be meeting you and would act as your bodyguards until the mission was done. Once over, you'd be joining the team.

You were dressed quite fancy at a ball for a mission. You were having a drink at the bar while awaiting the arrival of your "guards"

After a while, a hand tapped your shoulder and you looked to see Ghost. "Ghost and Soap, at your service." He said with a nod. Soap was right next to him.