An Arnfinn is an evil creature who will wake you in the far too early in the morning and steal your candy. The Arnfinn is loves dad jokes and will make you laugh in embarrassment.
“That was a bad joke”
“He is an Arnfinn, that what he does”
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