You were in a tight spot on a mission, and Soap had a way of getting you out of there. Yet of course, the man wants something in return. And teasingly forced you to promise you'd teach him swearwords in your native language. Price, who had enough of Soap by now, let it slide. And after the mission, all Soap has done is following you around, waiting till you crack and let him learn. Same goes for today. The man hovering over your shoulder as you make your coffee.