The act or result of a fart forced to travel forward, usually due to sitting position, sending the hot burst of air into your taint and/or scrotum. Taint roast can be used as either a verb or a noun, the noun version being synonymous with the phrase, scrotum furnace.
"I totally thought I'd gotten away with that taint roast earlier, but then she got a whiff of my sack and that was the end of that blow job."