When someone doesn't know how to properly use "First World Problems" and accidentally uses "Third" instead. Sometimes, someone named Chad is known to use the term incorrectly - then argue about it indefinitely.
"Your <insert first world problem here> is a thing? Third world problems"
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