Though I've seen a ok deal of anime movies, both subtitled and dubbed, I never came across the word wai until I started reading Megatokyo, and then I started noticing it in many other comics and people using it in conversation, usu. related to Sailor Moon on shoujo manga stuff. That might explain why I missed it, but I seriously want to know, as I haven't gotten a chance to take a Japanese course yet
"The basic tool for manipulation of reality is the manipulation of words. If you can control the meaning of words, you can control the people who must use them." - Philip K. Dick