When someone becomes more attractive to you when you haven’t seen them in a long time. Basically, your image of them in your head becomes more attractive.
Matthew: I thought you were over Terrry?
Sam: I haven’t seen him in a month, and you know what they say, absence makes the dick grow harder.
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