arse-backwards

1) Very wrong.

2) Right (rare usage)

1) "... It's a privilege to have people listen to your views, and if people get them arse backwards sometimes, that's the price you have to pay ..." -- Alexei Sayle, comedian, satirist and Young Ones co-star, after apparently dissing his home city.

2) Bill: I put my trousers on arse-backwards today.
Ben: Well done. That's correct.

by Mathilda Underfoot April 11, 2010