If you’ve ever wondered whether airport agents perform a necessary function, take a look at the TSA Instagram account. You’ll find a stupefying collection of objects confiscated from passengers, including axes, crossbows, and handguns (and that’s just in the last few days). Acting foolishly, though, can get you delayed from a flight or even detained. To help explain what you shouldn’t do in an airport security line, we tapped Lewis Sage-Passant, a former British infantry officer who is trained in intelligence and has worked in security and crisis management for several corporations, including Goldman-Sachs. These days, he runs How Safe Is My Trip, a company that creates advisory reports for people going to risky destinations. Below, check out his tips on what not to do in a security line.

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1. Don’t joke about bombs or anything illegal.

You’d be amazed at how many people think it’s no big deal to joke about having explosives on an airport security line. After being told that he couldn’t bring two cans of soda on board, a Phoenix passenger said each can contained a 30-second detonator. A customer in San Juan told the ticket agent her bag had a bomb and she was going to blow up the plane, causing the terminal to be shut down for almost an hour. A Miami traveler said he had a bag full of dynamite, and thus caused five flights and over 1,000 people to be delayed for almost five hours. (You can read a long list of people trying to drop the same gag.) “People are getting frustrated with airport security and the frustration is leading to people making jokes,” says Sage-Passant. “It’s a pretty thankless task from the point of view of the TSA. They’re screening about two million people every day just in the U.S.”

2. Don’t try to hide something that shouldn’t be on the plane.

In addition to numerous confiscated items, the TSA Instagram account also shows pictures of the many ways people try to hide objects that shouldn’t be on a plane. For example, one traveler hid a knife inside of an umbrella, assuming that no TSA officer would open it (since it’s bad luck). Another taped a pocketknife into the hollowed-out plastic handle of an electric toothbrush. Such craftiness can lead to fines and even arrest. If you’re wondering whether or not you can pack a particular item, tweet a picture of it to @AskTSA and the account managers will let you know. One vacationer recently sent a picture of a replica battle axe. (That needs to be placed in checked baggage, FYI.)

A common question is whether or not food can be brought through security. “You can bring through solid food, but they may ask to inspect it,” says Sage-Passant. “They’ll even open up people’s sandwiches. People who are trying to smuggle things into the airport are quite creative and will use things like that. But typically, food items are okay to carry through.”

3. Don’t smuggle too much liquid through the security line.

Anyone who has flown on a plane in the past 20 years should know that only 3.4 ounces (or 100 milliliters) of any liquid are allowed on a plane. So don’t slide that $5 liter of Diet Coke you just bought into your windbreaker pocket. The officers will make you throw it out.

4. Don’t bring a gun.

If you’re wondering whether or not you can bring a weapon on a plane, the answer is probably no. If the weapon is a gun, the answer is definitely no. In July 2017, a record 89 firearms were confiscated in the TSA line in one week. Sure, a few may have been found on gun holders who absentmindedly forgot they were carrying it, but that leaves more than 80 people who were actively breaking the rules.

5. Don’t re-pack.

While there’s nothing illegal or even technically wrong about reorganizing your carry-on while in the security line, you can’t pull this off without annoying everyone around you. As the line trudges forward, your clothes, laptop, and shoes will probably get mixed in with someone else’s and the sighs will start rolling. There’s plenty of time after getting through security to apply all of the Marie Kondo advice you’ve been itching to unleash.

6. Don’t get nervous if officers pull you out of line for questioning.

Sometimes the officers are trying to confirm a question they have or are doing a required random screening. “They’re not flying you off to Guantanamo Bay,” notes Sage-Passant. “Usually there’s something that has shown up funny on the X-ray and they just want another look at it.” If you’re in a hurry or feeling frustrated, cool your jets and remain polite.

Sage-Passant has gotten pulled out of the security line several times. When he was carrying his army-issued rucksack, TSA officers would find gunpowder residue on the cloth. But it didn’t take much of a discussion to clarify the situation. “As long as there’s an acceptable reason, the officers aren’t really looking to dive in,” explains Sage-Passant.

7. Don’t worry if you realize you have something you shouldn’t.

People often forget they’re carrying something that they shouldn’t, such as nail clippers, says Sage-Passant. “If it’s a genuine innocent mistake, they will let you go,” he says. “It’s when people get shifty or defensive that there’s a problem.”

8. Don’t wait to take off your metal.

No one wants to be the person who holds up a long line of annoyed people. You can avoid people staring at you with their arms folded by removing your watch, belt, jewelry, and other metal items long before you’re facing the TSA officer. Oh, and empty your pockets.

9. Don’t get grabby with other people’s stuff.

Wanting the line to move along quickly is understandable. Pushing another person’s iPad around is unnecessary. You never know what’s going to spark an argument when you’ve got a long line of grumpy travelers. If another traveler leaves something behind, you may even cause a security breach by picking it up (as surprising as that may seem).

10. Don’t unpack necessarily.

Many travelers assume they need to place all electronics into a bin, even though TSA rules specify that only electronic items larger than a cell phone must be X-rayed individually. So, yes, you need to separate out your Nintendo and iPad, but no, you don’t need to take out your iPhone.

11. Don’t hassle the TSA officers.

The security officers have to guide a lot of people through the lines each day, and they want to move you along as quickly as possible. If you get it in your head that they’re out to hassle you, the situation will likely get worse and tensions will escalate. Keep calm and move on.

12. Don’t forget to sign up for TSA Pre-Check.

If you’re a frequent traveler and groaning about waiting in yet another security line, you might want to seriously consider investing in TSA PreCheck, so your trip doesn’t feel even longer.

If you want the latest information on the TSA’s policies (which can change), check out the TSA blog as well as its most recent press releases.

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