foul one's own nest

verb2

1. •
   To damage one's environment.

   • Provide them with a mansion, and they will rip out the plumbing, write obscenities on the walls, and generally foul up their own nest. — 1992
2. •
   To hurt one's own interests, especially to damage the reputation of one's self, family or group.

   • He had concluded, 'Arbitrary violence against them now would be to foul your own nest; mar at the outset the future that is your destiny. — 2007