Multilingual

It's pretty convenient to be able to speak more than one language. If you are in a crowd of people and want to say something to the person next to you without others understanding, you just switch to another language. Tonight while hanging out with some of my girlfriends, we were having a hard time making a decision about whether or not to go to an upcoming event. After debating for awhile, we settled for doing rock-paper-scissor. When a couple of the boyfriends called, instead of saying "hi" we said, "yes or no?" Without knowing what the question was for, both guys who called said, "yes." While I was asking Bertrand this question, one of the girls put up two of her fingers and said, "Ask him how many fingers I'm holding up." I spoke to him on the phone and said, "Hai" and he responded with "Two." The girls were in awe. How did he guess? "Hai" in Vietnamese means "Two", but all the girls heard me say was "Hi."