foul one's nest

foul one's (own) nest

To do something that creates problems for oneself. I wouldn't talk to the boss while you're angry—you'll just end up fouling your own nest.
See also: foul, nest

foul one's nest

Also, foul one's own nest. Hurt one's own interests, as in With his constant complaints about his wife, he's only fouling his own nest. This metaphoric expression transfers a bird's soiling of its nest to human behavior. [Mid-1200s]
See also: foul, nest