That's when you turn around an pop an eyebrow like The Rock, and if they don't take the hint, you tell them to STFU or leave. The second time I went to see Chef, it was driving me nuts. I swear it seemed like this older couple behind my buddy and I were recording their own commentary. At one point, a character's about to turn and smile at the protagonist. One second before, "she's going to turn around and smile at him." "That kid's cute. You know who he reminds me of? Becky's...no, not Becky's, Charline's little boy...blah, blah, blah, blah, blah." It's like "I didn't pay $6 to hear you speak, I paid $6 to hear Jon Favreau and his co-stars act out a story, which requires them to speak. I can't focus on their speech, if you're interrupting them at every turn with a rant about how the kid playing his son looks like Becky or whatever the hell her name is' kid."
For the record, these people were past middle age, but they weren't at that point where they get a free pass because you think that, maybe, they don't remember their names, let alone society's standards on keeping your mouth shut during the movie.