The term used to describe the itching of the anus at night, due to threadworms. Whilst sleeping your body automatically scratches the irritation but it only gets eggs under your nails to produce more thread worms and gives you a nasty smelling hand.
"Dude, I have a proper bad case of analirritation. I need to get checked out."
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi