If we look at bilingual children communicating with each other by using L1 and L2 in their communication, we may wonder what notion makes them start in one language and then switch to the other language while talking to the same person. We often observe international students on the CHU campus choosing their mother languages to communicate with friends from their home countries, the suddenly switching to English when talking to others from a different country. Code-switching occurs in many circumstances, not just in multicultural situations, but also among immigrant populations. The phenomenon of switching among languages can cause very interesting interactions in people's daily lives.