This one comes from the Washington Post. It is a mashup of “throw a (monkey) wrench in the works” (to do something that prevents a plan from succeeding) and “knock (someone) sideways” (to upset, confuse, or shock). Maybe “thrown (someone) for a loop” (to confuse or shock) is also in the mix. The expression “throw a (monkey) wrench in the works” seems to be garbled a lot. I have posted several malaphors involving the expression, including “throw another kink in the fire”, “a wrench had been thrown in the bucket”, and “he really threw a monkey wrench into that fire”. https://malaphors.com/2017/11/01/throw-another-kink-in-the-wrench/, https://malaphors.com/2016/10/04/a-wrench-had-been-thrown-into-the-bucket/, https://malaphors.com/2013/02/08/he-really-threw-a-monkey-wrench-into-that-fire/
Here’s the cite:
A tip of the hat to Barry Eigen who spotted this timely malaphor.