spike someone's guns
spike (one's) guns
To ruin one's plans or prevent one's success. The phrase refers to the former military practice of inserting spikes into enemy guns to prevent them from firing. I'm afraid the rain has spiked our guns. We cannot hold the rally as planned.
spike someone's gunsBRITISH
If you spike someone's guns, you do something to prevent someone's plans from succeeding. Parkers spiked their rival's guns by launching their product two months before Jones were able to do so. Note: In the past, when soldiers captured a large enemy gun which they could not move, they hammered a nail or spike into the hole where the gunpowder was put. This meant that the gunpowder could not be lit and so the gun would not work.
spike someone's gunstake steps to thwart someone's intended course of action.
First recorded in English in the late 17th century, the expression referred literally to the practice of hammering a metal spike into a captured enemy cannon so that it could not be fired.