Dick Clark Aging

We were in fourth grade, and my friend Dawn's older brother owned the entire series of Truly Tasteless Jokes books. The following joke appeared in one of them:

Q: What goes "40, 39, 38, 37, 36, 35....?"
A: Dick Clark aging.

I read it and was like, "Hahahahaha, oh that is RICH. Wait, I don't get it."

R.I.P.