or ass·back·ward

[ as-bak-werdz ]

adverbSlang: Sometimes Vulgar.
  1. in an order or way reverse from the usual: You've sewn the sleeve on assbackwards.

  2. in a manner incongruously or preposterously counter to what is customary, probable, or feasible: The plan fell apart because everything leading up to it was handled assbackwards.

Origin of assbackwards

First recorded in 1935–40; ass2 + backwards Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use assbackwards in a sentence