He said "gao wan!"

If you know for a fact that nobody around you can hear/understand what you're saying, that's basically a free pass to talk about whatever you want. This applies to people who go hiking by themselves, adults who talk about "grown up things" in front of the kids, friends who have code words for other people, and people in the U.S. who speak any language other then English. This also applies for Taiwanese students in the presence of their English teacher who doesn't know any Chinese. The difference is, recently I am able to understand a lot of what they are saying, and they don't know!!

"The History and Evolution of the Peace Sign"

I just found this video, thought you'd like to see it: