This is such a basic question and probably many of you have never even thought about it, but would you say something?
Say you were at the grocery store and the express aisle was 12 items or fewer, and you were in a rush, and someone in front of you in line had clearly 25+ items. Would you say something? Why or why not?
But inside I’d be singing “12!12!12!12! Let’s sing a song of 12! How many twellllllllve?”
I wouldn’t say anything. Unless I was behind them the whole time, how would I know that they didn’t speak to the cashier about if it was okay that they have too many items? I’ve heard cashiers with no line invite people with a few too many items to come to their registers often enough not to assume that the person’s just being a jerk.
Honestly, the experience is so rare, I’ve forgotten it if it ever happened. The cashiers are fast. If there’s a hold up, it’s because the customer has only just decided after everything was rung up that they wanted to write a check or they had coupons.
Challenge them to a duel.
In life, 99% of the time I get what I want in the quickest and most efficient manner by going with the flow. Stopping and making a scene will take much more of my time than just waiting for the 25-item person to move through the line. There are times for rules lawyering, when the stakes are higher. This is not one of those times.
I give them a very stern looking-at.
ETA: My husband and I will sometimes have a very passive-aggressive loud conversation about how some people can’t count very well. 
Go full blown Dirty Harry on their ass. They’re the most contemptible species of vermin on Earth. You can go on about yer rapists, yer murders and drug dealers, yer pedopoholophile child molestators, but in my book there ain’t no lower life form than somebody who is in the express line with more than 12 items. A quick death is too good for them.
If they haven’t unloaded their cart yet, I might point out the sign right above the cashier that they must have missed. But if they’ve already unloaded their cart, there’s no point in saying anything. (Still, the store could add an item count to the register display, so they’d know by how many items they undercounted.)
If I know that they weren’t invited to the lane by the cashier, I’d say something. Rude people depend on people not calling them on their bullshit.
I’d start singing this, if it was way over.
They always seem to call me over to an expess lane when I have a full cart. I used to go and feel like an ass the entire time I was being rang up. Now I politely decline to get in the fifteen item lane,explaining that I’m tired of being thought an ass. They often manage to open a new lane.
Another lop sided poll. Really, who has time to get upset about this?
I manage to squeeze it in.
This, accompanied by an eye roll. But never where they can see it.
Roddy
I got to witness the very amusing results of option #2 at Whole Foods yesterday. There was an extraordinarily long line at the express lane, probably at least 25 people, that went almost the entire length of the aisle. It was moving fairly fast, and I wasn’t in any hurry. But a guy a few spots behind me clearly was. All he was buying was a single bottle of milk. All of a sudden he exclaimed something to his companion, and then broke for the head of the line. He went straight to the cashier and started arguing. The customer who was being waited on naturally got upset, and there was a confrontation that resulted in the line jumper coming back to the line and asking if he could resume his original place. I overheard him whining to his companion that this line was for people with 1, 2, 3 or 4 items, while the customer checking out clearly had more than that, but had been extremely rude and refused to allow him to go ahead. I considered pointing out to him that the sign with the “1, 2, 3 or 4” on it was referring to the lane numbers, and that it clearly indicated that the people in those lanes needed to have 10 items or less. But he didn’t seem like he would be very receptive to an explanation. After I checked out my one item and went outside, I saw him in the parking lot still complaining about his ill treatment.
Damn right I tell them. But then, express lanes here are still 6 items or less, so violations are even more egregious.
Be careful. Around here, people carry guns to the grocery store.
http://crime.blogs.tuscaloosanews.com/16276/man-wounded-after-dropping-his-gun-in-a-tuscaloosa-store/
Ignore it. BFD.
Sometimes it’s an accident. One time my 75 year-old Mom got in one with probably thirty items. She hadn’t noticed the sign. The cashier made her load them back into her cart, probably taking longer than if she’d just rung up my Mom, and made her go into another line. My Mom was mortified. I was ready to kill that clerk-it was an honest mistake and she didn’t have to humiliate my Mom.