If an inappropriate question turns you sour on the position, consider it a blessing in disguise and fodder for a good story. (topresume.com)
They are called buttermilk because if you didn't know, you can make buttermilk out of regular milk by adding vinegar to it, which in turn makes it sour. (mynaturalfamily.com)
It's this kind of crap that turns me sour toward gurus! (biggerpockets.com)