Use this term after describing something you used to do, or before you describe something that happened to you. The phrase can be said just by itself if in the right context, to mean "Oh yeah we used to do that all the time"
"Hey remember when we used to always play poker on Wednesdays?" "Dude, Back in Nam"
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