It seems that when God was making the world, He called man over and
bestowed upon him twenty years of normal sex life. Man was horrified!!
"Only twenty years of normal sex life?" But the Lord was very adamant;
that was all man could have.
Then the Lord called the monkey and gave him twenty years. "But
I don't need twenty years", he protested, "ten is plenty for me". Man
spoke up eagerly. "Can I have the other ten?" The monkey graciously
agreed.
Then the Lord called the lion and gave him twenty years; and the
lion, like the monkey, wanted only ten. Again man spoke up: "Can I have
the other ten?" The lion said of course he could.
Then came the donkey and he was given twenty years. But, like the
others, ten was sufficient, and again, man pleaded: "Can I have the
other ten?"
Which explains why man has twenty years of normal sex life, ten
years of monkeying around, ten years of lion about it, and ten years of
making an ass of himself.