Blue means "take a nap"

Oh, you were unaware?  Blue means take a nap!  A couple of weeks ago Gavin started talking about the traffic lights and what they mean.  He learned pretty quickly that green means go and red means stop.  Then, of course, he asked about yellow.  Instead of trying to really explain it, I told him it means "caution."  Then a few times he tried to tell me that blue also means go.  I went along with him for a little while.  Then he started asking me.  "What does blue mean?"  I'm sure we were taking one of our "buh-rides(driving around for the purpose of getting him to sleep)" so once when he asked I just blurted out "Take a Nap."  So now if you ask him what blue means, he will in fact say, "take a nap."