Brain, where did you hide my English?

My friends and I were talking, and they were all saying this word I had never heard before, and I really couldn't understand the conversation without knowing the meaning of the word.  The word "shaiboi" just kept coming up!  So I asked "Shaiboi no imi wa nan desu ka?" [what is the meaning of "shaiboi"?] and as I said it out loud, I realized what I was saying.  Yuuka and I had a little movie-moment where we both kind of froze in the mutual confusion, and then burst out laughing.  "Ohhhhhhh eigo desu!!!"  It's English!  "Shy boy."  Silly me.  My brain assumed it was Japanese; it didn't even occur to me that it was English.