Elyse Welles was traveling from Athens, Greece, to Newark, New Jersey, this past spring when it finally happened: She was pulled aside for an additional security screening at her gate.

After some time searching through Welles’ backpack, the agent eventually grabbed a bullet-shaped vibrator from the bag and brandished it in the air. “Is this an e-cigarette?” the agent asked. “No, it’s a sex toy,” she responded with a smile, at which point her personal items were promptly returned to her and she was free to go.

Welles, a writer and life coach who lives in Artemida, Greece, said she didn’t give a second thought to traveling with her vibrator in tow.

While sex toys are accepted carry-on luggage in most countries, including the United States, there are certain restrictions when it comes to e-cigarettes on flights, because the devices could catch fire in transit.

As the number of air travelers rises, returning to near-pre-pandemic levels, so do questions about flying protocols and rules — particularly what travelers can and cannot take in their carry-on luggage when flying within the United States. For instance: Is guacamole a solid or a liquid? (It’s a gel, which falls under the same restrictions as liquids and is not allowed in your carry-on — unless it’s inside a 3.4-ounce container.)

Here’s a guide to help you navigate the more ambiguous carry-on rules — with some quiz questions throughout to test your knowledge, too.

Let’s talk a little more about vibrators. Although most sex toys, including vibrators, are allowed in your carry-on, according to the Transportation Security Administration, they may still lead to a stop, as in Welles’ case. There are some ways to reduce the chances of these uncomfortable encounters, especially if something starts buzzing.

Shan Boodram, an intimacy expert and host of the podcast Lovers and Friends, suggests removing any batteries or running batteries of rechargeable toys out before packing them. “Or, find a hard case to put it in that’s slightly larger so the power button has less of a chance of being pressed when pressure is applied to your bag,” she said.

There are also vibrators with built-in travel settings now, to prevent them from going off at an inopportune moment, such as the Surge silicone rechargeable vibrator, which has a built-in travel lock.

“The most common mistake that we see people making in terms of prohibited items at airports are large liquids, gels and aerosols in carry-on bags,” said Lisa Farbstein, a spokesperson for the TSA.

TSA’s widely publicized 3-1-1 rule dictates that passengers may travel with liquids, gels and aerosols as long as they’re in 3.4-ounce containers in one quart-size resealable bag. So while a bottle of water won’t make it through a preflight screening, what about something in a more nebulous category, such as a jar of peanut butter?

“If you can spill it, spread it, spray it, pump it or pour it,” Farbstein said, “it is a liquid, gel or aerosol.”

This is why a Magic 8 Ball, which is filled with liquid, is not allowed through a TSA checkpoint. The same goes for a snow globe. Unless, of course, as Farbstein points out, either is a version that’s small enough to fit inside a traveler’s 3-1-1 bag.

The 3-1-1 rule was imposed after terrorists in Britain tried to sneak liquid explosives in planes in August 2006. It’s these kinds of explosives that dogs are searching for when they sniff passengers’ bags at airports, Farbstein said.

“TSA is not looking for drugs,” Farbstein said. “Our dogs sniff for explosives; they don’t sniff for drugs.”

But just because they’re not looking for drugs doesn’t mean agents never find them. If they do, TSA officers are required to report suspected violations of law to police, Farbstein said. And although marijuana has been legalized for recreational use in 19 states and for medical use in 37, it’s still illegal under federal law and is thus restricted on airplanes, even if it is technically legal in both the departure and destination states.

Some plant lovers may want to fly home with a new addition for their collection.

Plants are allowed on domestic flights as long as they fit in the overhead bin or underneath the airplane seat, according to the TSA website. Returning with potted plants from abroad, however, is prohibited, although a limited number of bare-root plants (not in soil) are allowed, as long as they meet certain criteria set by the Department of Agriculture’s Animal and Plant Health Inspection Service. There’s also additional information for travelers arriving to the U.S. mainland from Puerto Rico and the U.S. Virgin Islands.

“I always have my eye out for beautiful, healthy specimens of rare plants, so I like to snag them when I see them,” said Lexi Osterhoudt, a doctoral student in Columbia University’s Integrated Program in Cellular, Molecular and Biomedical Studies. Oftentimes, she said, her plant souvenirs are impulse buys she picks up while traveling domestically, or they’re good finds that are more affordable than they would be if she bought them in New York, where she currently lives.

“I’ll Saran Wrap the pot to keep the soil together, put them in a paper bag and stick them under the seat in front of me,” she said.

If any more clarification is needed, the TSA has provided an extensive and searchable list where travelers can look up whichever items they’re concerned about bringing. Knitting needles, for example, are allowed in your carry-on, as are live fish, provided they’re in water and a clear transparent container. But wait — isn’t there a liquids rule?

“Live fish are indeed allowed to be transported through a security checkpoint,” Farbstein said. “And of course to keep them alive, they need to be in water. TSA officers will screen the container of water that the fish are contained in. It will take additional time for the screening process. Live fish in water do not need to meet the 3-1-1 rule.”

Cremated human remains get a little more complicated, while cricket bats and cutting boards are best left in checked luggage. Musical instruments such as violins are allowed after they undergo a TSA screening, but for brass instruments, the suggestion is to check them. And if you’re a Harry Potter fan, fear not — wands are allowed on flights.

Despite the TSA’s rules, there’s one item in particular that Farbstein said she still sees confiscated far too often: knives. “We see knives every day,” she said.

As many as 4 tons of different kinds of knives and large tools get confiscated at Newark Liberty International Airport in New Jersey in an average year, according to Farbstein. The TSA then sends them off in bulk to the state of Pennsylvania, she said, which sells them for profit at a surplus store in Harrisburg.

Travelers should remember that knives of all kinds are not allowed on flights, Farbstein said.

Something that won’t get confiscated? A duffel bag holding eight rolls of Goetta sausage. However, it might land you on the TSA’s Instagram account.

This article originally appeared in The New York Times.