Doonesbury by Garry Trudeau for February 10, 1976
Transcript:
Man: Joanie, what are you trying to ask me - whether I love you? If you are, the answer's yes... Joanie: Oh.. no, Andy, I'm not trying to pinyou down... I... Man: But, Joanie, there's something you have to know... I guess I should have told you a while ago... Joanie: You're married, aren't you? Man: No, Joanie, I'm gay. Joanie: Well, what's wrong with that? I'm usually cheerful, too! Man: No, I mean... Joanie: Oh, my God...
Even at the time this was first published, it seemed to me to be like the final nail in the coffin for “gay” as defined as happy or cheerful or festive.