an adverse reaction to some political or social occurrence
There was a backlash of intolerance.
source: WordNet 3.0
The distance through which one part of connected machinery, as a wheel, piston, or screw, can be moved without moving the connected parts, resulting from looseness in fitting or from wear; also, the jarring or reflex motion caused in badly fitting machinery by irregularities in velocity or a reverse of motion.
source: Webster 1913
come back to the originator of an action with an undesired effect
Your comments may backfire and cause you a lot of trouble.