pain in the keister

pain in the keister (plural pains in the keister)

1. (slang) Synonym of pain in the ass.
   • 2016 June 10, Rianne Coale, “How to avoid tickets, towing and more in the city, a guide for Chicago drivers”, in Chicago Tribune‎^[1]:

     Well, if you've been unlucky enough to be graced with a bright orange envelope on your windshield (*face-palm*), you'll know what a pain in the keister it is.