Here's what started the "candidates on comedy shows".

1968:

[The Nixon episode of "Laugh-In"] was broadcast at the height of Nixon's (ultimately successful) campaign against Vice-President Hubert Humphrey, and was an immediate sensation. George Schlatter, the creator of "Laugh-In" ... told me that Nixon had been extremely reluctant to be on the show; although the producers had repeatedly entreated him to appear, his campaign aides had even more insistently urged him not to. Eventually, the race brought Nixon out to Los Angeles. He gave a press conference, and Schlatter and one of "Laugh-In"'s writers, Paul Keyes, who happened to be a close friend of the former Vice-President's, went over to watch it, bringing a TV camera with them.

"While his advisers were telling him not to do it, Paul was telling him how much it would mean to his career," Schlatter recalled. "And we went in, and he said, 'Sock it to me.' It took about six takes, because it sounded angry: 'Sock-it-to-me!' After that, we grabbed the tape and escaped before his advisers got to him.

"Then, realizing what we had done—because he did come out looking like a nice guy—we pursued Humphrey all over the country, trying to get him to say, 'I'll sock it to you, Dick!'" Schlatter went on. "And Humphrey later said that not doing it may have cost him the election. We didn't realize how effective it was going to be. But there were other factors in the election, too—I can't take all the blame."

Nixon on "Laugh-In" is often cited as a watershed moment in the history of television—the unthinking man's version of Nixon in China.