these scenes are called 'wacca wacca scenes'
basically if you can't think of anything to talk about you say "wacca wacca wacca" like Pacman, giving the illusion that you are actually talking.
Teamed with facial expressions it generally works as long as noone is wearing sunglasses and watches.

sometimes they're cast to be "the couple talking in the background" but they do use real people who are just eating and talking. One of the things the director will do is record all the background people talking simultaneously and then when they shoot the scene the extras will just move their mouth with out talking. They tell us to say "peas and carrots" back and forth to each other but it really doesn't matter you could mouthing the most graphic obscene thing you could imagine as long as you aren't acting like a maniac. Editors will put in the the real conversation over the tape for mild background noise. I know this because I was an extra on a lot of movies/tv shows when i was younger.

Care to list any movies you were in?

role models, handful of disneyland commercials, a few tv shows here and there, etc

They were filming a movie or something one time while me and my parents went out for coffee. The people just talked about random **** . And every time they had to retake the film, they'd just keep talking. Pretty sure they just start talking about whatever

the other day i was walking around downtown NY and like 4 guys with scripts and headphones asked me if i wanna be in a hollywood movie... i said know cuz i thought it was a scam... i wonder if it wasn't


almost all of the good actors today started out as a background character with like 1 line or line at all