Good one to know!Седина в бороду, бес в ребро.
It reminds me of a famous quote attributed to an ancient Greek guy who had reached the age of 80 or so, and someone asked him whether he still got horny: "No," he said, "at long last I am free from that cruel and insane master!"
P.S. From Googling, I discovered that this was attributed to Sophocles by Plato, in The Republic -- so who knows whether Sophocles really said it or not.
...P.P.S. And with a little more help from Google, I find that it is has been translated into Russian as «я с величайшей радостью ушел от этого, как уходят от яростного и лютого повелителя».