Now THIS is where we get into taboo territory in my mind, but, while it's not in my active vocabulary in this sense of the word, I like it too.
yeah, shagged is maybe a little naughty, but I'm not entirely sure where @matwoolf gets the impression that knackered has the same origin. Knackers are slang for balls, but the word 'knackered' was used to describe unwell animals on farms, like horses that were no use any more. Hence when you're knackered, you're worn down. Never heard anything to suggest it meant tired after intercourse ...
Hello @AlannaHart , I assure you I know better, if you check the profile you will see I am English. You are Australian, I believe. 'Knackered' is a 20c euphemism type pas devant les enfants sort of thing, otherwise I look like an idiot. http://www.urbandictionary.com/define.php?term=Knackered YES, YES, YES HEH HMMMMM EURRRRRRR
I actually am English @matwoolf I go back and forth to Australia to see family, and I lived there at the time I got this account. I live in Hampshire. Was only pointing out that I've never heard that association with shagging and when I looked it up could only find the farming origins. Don't get high and mighty.
I would take a different approach and stop saying it too much. The condition should be "shown" and the reader concludes it on their own. Say it less, show it more. One eye, already weakening. Foggy eyes. Slow reactions. Tonight might require 2 toothpicks per eye, instead of the usual one. etc. John Krone