foul one's own nest

foul one's own nest (to harm one's own interests; to bring disadvantage upon oneself) — навредить себе; сделать себе хуже; гадить там, где живешь

Example 1: She was right. I had fouled my own nest last night and today. I did not intend it to happen again. (Anne Rivers Siddons, “Low Country”, 1998)

Example 2: The boss really dislikes Mary. She certainly fouled her own nest when she spread those rumors
about him.
(NTC's)

Example 3: The hybrid and doubtlessly controversial notion of refugees used in this study is people who feel compelled to flee across international borders from disruptions they see as life-threatening and over which they have no control. The requirement that disruptions be life-threatening eliminates refugee eligibility from less severe forms of turmoil or deprivation, while the stipulation that the refugees are not in any way responsible for these disruptions eliminates such eligibility for those who have fouled their own nest. (Armed Forces & Society )

Example 4: It's not just the fact of global warming but the psychology of any people that are irresponsible and foul their own nest. When I go, I hope it will be a case of "The Little Man Who Wasn't There" and there won't be a lot of garbage around after Sonny Rollins leaves.
(Chicago Tribune)

Example 5: Not in any panicky way, with visions of the oceans covering our coasts and our forests turning into tropical jungles, but with a calm, clear-eyed resolve, based on the understanding that it's a dumb idea for any creature to foul its own nest. The junk we've been putting into the atmosphere can't possibly do us any good, and there's a reasonable chance that it can do us great harm. Therefore we should clean up our act, not by closing down the factories and switching overnight from cars to bicycles, but by zeroing in on the chief causes of pollution and finding rational ways of eliminating them, and by putting programs of energy conservation into use.
(Omni)

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Alludes to a bird excreting into its own nest. See It’s an ill bird that fouls its own nest.

Related Vocabulary
[score one's own goal]
[себе во вред]
[ride for a fall]
be one's own worst (enemy to cause a lot of problems for yourself because of your own behaviour) — сам себе враг