This an act you do with your sexual partner with a vehicle, it's when your partner turns on a car, puts it in park and revs the engine as hard, whilst you insert your dick into the exhaust pipe and start fucking the car exhaust pipe while they are revving the engine causing your dick to burn
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