royal pain

plural royal pains

1. derogatoryoftenslangSomeone or something that is very annoying.

   In fact, the only thing royal about you is that you are a royal pain!

   2011, Amy Keating Rogers, The Best Night Ever, spoken by Rarity

   1 more example

   And while the spine's no doubt a miraculous array of vertebrae, ligaments, muscle and nerve tissue, it can also be a royal pain in the... well, lower back region.

   1992 February, Cincinnati Magazine, volume 25, number 5, page 71

2. derogatoryoftenslangA feeling of being very annoyed.

   He gave out a big yawn while he said that. Which is something that gives me a royal pain in the ass.

   1951 July 16, J[erome] D[avid] Salinger, The Catcher in the Rye, Boston, Mass.: Little, Brown and Company, →OCLC, page 37