A scorpion and a frog meet on the bank of a stream. The scorpion, who cannot swim, asks the frog to help him cross the river by carrying him on his back.
The frog is hesistant, and asks: "How do I know you won't sting me?"
The scorpion replies: "It doesn't make sense for me to do that, because if I do, I will die too."
The frog thinks for a moment and is satisfied, and they set out.
However midstream, the frog feels a sharp pain in his back. The frog feels the onset of paralysis and starts to sink, knowing they both will drown.
He has just enough time to gasp..."Why? Why did you sting me?"
Replies the scorpion: "I'm sorry, I could not help myself...it's my nature."