I've used "gay" to mean "happy" - the word was taken by the homosexual community in either the VERY LATE 80's or the very early 90's, more likely the early 90's. I had used it for at least 10 years at that point.

The odd thing was that only two years later, an 11-year-old child snickered at hearing the song "When Irish Eyes Are Smiling" because it had that word in it. His mother knew what it meant. How soon we forget...