Not the scorpion and the frog
I liked this bit from The Good Wife (season 1, ep 14, “Hi”):
Cary: I can't help it, you know, being competitive, it's just me.
Alicia: Oh, nononono. Not the scorpion and the frog story, please.
Cary: [Laughs.] The scorpion on the frog's back, yeah, I hate that story too. Why do people tell it so much?
Alicia: Because it excuses people's behavior.