Did the cashier give off body language suggesting they closed the line due to not liking the guy behind you?
I don't know under what circumstances a cashier might open a line only briefly, but I often realize I forgot something right when I start an activity.
But yeah, if they caught a glimpse of the guy behind you and then closed down in a pissy way, I'd probably start by offering to be a supporting voice during a complaint to the store management. If it's any kind of pattern, the cashier will likely be out of a job.
An irreverant/fantasy show with sypathetic well-intentioned protagonists, at minimum understandable volume, with characters and plotlines that invite analysis. Something about the pointlessness of studying a fantasy universe is a quite effective sleep aid. Various Star Trek series, Futurama, X-Files, Grimm, Family Guy...
For shows that are a great fit except for a few segments (boisterous theme songs, jarring fight scenes, etc) the PotPlayer Skip Playback function (hotkey ') is super useful. Also I have a basic script that gradually mutes the volume after 40 minutes.