A routine send-off. The origin is from the airlines, when the flight ended, and stewardesses badefarewell to planeloads of passengers as they filed out.
Passenger 1: "Enjoyed the flight."
Stewardess: "Buh bye."
Passenger 2: "See you next trip."
Stewardess: "Buh bye."
Passenger 3: ""Bye now."
Stewardess: "Buh bye, buh bye, buh bye, buh bye...."
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