/as"bak"weuhrdz/ , adv. Slang ( 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.
Also, assbackward .
[ 1935-40; ASS 2 + BACKWARDS ]