Fairly recent discovery (like last couple years): people in videos doing ahegao. Especially the camgirls. I'm talking the stereotypical eyes crossed/rolled up, twin Vs, tongue out drooling one.
It's an expression at that exact moment when the girl cums too hard or goes cock-dumb, so it really only works in manga/picture format. And what do these real life people do? Hold the expression and zoom in on it, which means I'm stuck watching a girl making silly faces. Or what the camgirls do, consecutive ahegao faces like they're taking selfies. They're not even trying to pretend to be turned on. They're separating the expression from what it represents, and all you're left with is something empty. And silly-looking.
Actual cock-dumb expressions? Hot as hell. Watch the girl get dick and involuntarily twitch and go all quiet and their eyes roll a bit? Instant hard-on. This manufactured, standardised one? Makes me want to slap a bitch.