Totally off topic, but it's funny how much of "modern" slang (whatever the generation) is present in hip hop culture years before. I noticed that when "twerk" became a thing; I remembered songs about twerking from years before that.

In this case, the term "bet": I remembered hearing that for the first time in the late 1980s in a song by Fresh Prince (Will Smith): "... bet, well let's go then..." (As We Go, 1988)