Comment by wanderingstan

My go-to technique has been to offer the offender a pair of headphones, saying something to insinuate that they must forgotten theirs or be too poor to afford them. Most of the time they say “oh I have headphones!” and then realize that they’ve outed themselves. (I stockpile the free headphones from gyms or airplanes, or get the $2 ones from AliExpress)