Meaning of dirty tricks

dirt'y tricks'

Pronunciation: (dûr'tē trik'u-rē), [key]
— Informal. Informal.
  1. unethical or illegal campaign practices or pranks intended to disrupt or sabotage the campaigns of opposing candidates.
  2. any similar practices carried out against rival countries or corporations for espionage or commercial purposes.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.