Some laws seem pretty sensible. Others…well, not so much.

Dive into the hundreds of local ordinances, state laws, and federal statutes that make up your jurisdiction’s legal code, and you’re bound to find a few confusing entries. For instance, you might not know that…

1. Pro petsitters have a hard time working in New York City.

The city’s Department of Health and Mental Hygiene notes that according to city regulations, anyone petsitting for pay must have an official license for boarding animals. Additionally, inspectors must visit the pet sitter’s residence to approve their “kennel.”

The good news is that the law is rarely enforced unless the health department receives complaints. However, in recent years, pet-sitting apps have challenged the long-standing law.

Senator Tony Avella, a Democrat from Queens, recently filed a complaint against one pet-sitting app.

“This is being done as a business,” Avella said to The New York Times. “They should have the proper certification, the proper training and the proper place to house these animals.”

One pet sitter, 27-year-old Raul Cordero, disputes that assertion.

“So if you have a license, that means you are certified to feed a dog or a cat?” Cordero said. “That’s crazy.”

2. Many cities and states regulate haircuts.

As long as there have been barbers, parents have been circumventing them with a pair of scissors or a set of clippers. Cutting your own hair or your children’s hair is, of course, perfectly legal. Try to expand the business, though, and you may run into legal trouble.

That’s because barbers and hairstylists are subject to licensing laws set by cities and states. This may seem like a governmental overreach, but the reasoning is pretty sound. Giving shaves with straight razors or using chemicals to bleach and color hair can be dangerous.

And while it’s technically illegal to charge a neighbor or cousin for a haircut, the authorities probably won’t bust you if you’re not causing trouble in some other way. However, cutting hair without a license can serve as an excuse to pile charges onto someone who is already in trouble.

For instance, police made a routine check of licenses in a New York City barber shop and discovered that two of the men did not yet have their licenses. In their defense, it’s a complicated, two-year process to obtain a barber’s license in NYC. One of the men, Daniel Rodriguez, received a simple summons for barbering without a license, but for the other man, known only as Q, the situation was far worse: there was a warrant out for Q, so police arrested him on the spot.

Thankfully, the police go easier on barbers than they do on more hardened criminals. “They were gentlemen about it,” Rodriguez told The New York Times. “They let him finish the guy’s hair who was in the chair.”

3. AirBnB is illegal in some places.

An AirBnB host in Santa Monica, California, named Scott Shatford “agreed to cease operating in Santa Monica, pay the City approximately $3,500 in fines and investigative costs and pay hundreds of dollars more in criminal fines and restitution,” according to the Santa Monica Lookout.

As if thousands of dollars in fees weren’t enough, Shatford “was also placed on probation for 24 months,” explained the Lookout.

Santa Monica adopted a “home-sharing” law in May 2015, outlawing “the rental of an entire unit for less than 30 days, requiring City business licenses, and payment of Santa Monica’s 14 percent hotel tax.”

A similar law is on the books in New York City and other municipalities across the globe.

4. Wisconsin has some strange butter laws.

Wisconsin resident Julie Rider smuggles her favorite butter, Irish-made Kerrygold, across state lines.

“You can go over the border into Illinois or Minnesota and [buy Kerrygold],” she told the Chicago Tribune. “The dairy industry has a stranglehold on our legislators.”

According to the Tribune, “butter sold in Wisconsin [is] graded for taste, texture and color through a federal or state system,” meaning artisanal butters or those from abroad are prohibited in the state.

“We’re not a butter hit squad,” though, says Wisconsin Food and Recreational Safety administrator, Steve Ingham.

The Tribune goes on to specify, “The law also says state prisons, schools and hospitals may not swap out butter for margarine except for health-related reasons.”

Oh, and Wisconsin isn’t the only state with strange butter laws. In Iowa, it’s a misdemeanor to try to pass off margarine as butter. We can sort of understand that one.

5. Billboards are illegal in Hawaii.

Four states have actually banned billboards: Maine, Vermont, Alaska, and Hawaii. Hawaii’s law has been on the books the longest.

This is one of those laws that seems unusual, but makes sense when you think about it. Hawaii is known for its breathtaking scenery, and large outdoor advertising could realistically threaten the state’s natural beauty.

According to state law, companies can only display signs outside of the building where they do business. Signs aren’t permitted above the first floor, and the size of each sign is limited based on the size of the building.

6. In Delaware, you legally can’t sell dog hair.

The offense results in a disorderly conduct charge. You can’t sell the hair of any type of dog for any reason. We’re assuming that the law has something to do with 101 Dalmations, but we couldn’t find any justification for the odd regulation.

Oh, and you can’t sell cat hair, either. It’s a Class B misdemeanor. So if you’re running a black-market business selling prime Rhodesian Ridgeback fur, you might want to keep your operation on the down-low.

7. In Carmel, California, you’re not allowed to wear high heels.

Yes, it’s a real law:

The wearing of shoes with heels which measure more than two inches in height and less than one square inch of bearing surface upon the public streets and sidewalks of the City is prohibited, without the wearer’s first obtaining a permit for the wearing of such shoes. (Ord. 87 C.S. § 1, 1963; Code 1975 § 639.2).

According to a post on TripAdvisor, the strange law isn’t enforced. Apparently, it was added to the books in 1920, but these days, locals consider it a joke.

With that said, one user notes that high heels do carry certain risks.

“However, be very careful on the side streets, some of which can have some uneven pavement. Also, if you’re going to be walking in your heels after dark, it’s not a bad idea to have a small flashlight in your purse. Again, some of the side streets are not well lit.”

8. In Massachusetts, you can’t play part of the “Star-Spangled Banner.”

If you’re going to play the national anthem of the United States, you’d better play the whole thing. According to the law of the commonwealth:

“Whoever plays, sings or renders the ”Star Spangled Banner” in any public place, theatre, motion picture hall, restaurant or cafe, or at any public entertainment, other than as a whole and separate composition or number, without embellishment or addition in the way of national or other melodies, or whoever plays, sings or renders the ”Star Spangled Banner”, or any part thereof, as dance music, as an exit march or as a part of a medley of any kind, shall be punished by a fine of not more than one hundred dollars.”

Well alright then.

9. In Nevada, you can’t use x-rays to determine a person’s shoe size.

This seems like a strange place to draw a line, given that the state is known for its lax attitude towards…well, pretty much everything.

However, this law makes some sort of sense, since shoe-fitting fluoroscopes actually exist. From the 1920s to the 1970s, shoemakers used these “Pedoscopes” to fit customers for shoes. X-rays are a form of ionizing radiation, however, which means that they can potentially cause cancer in high doses. As such, Nevada’s legislators apparently decided to step in (pardon the pun).

This law shows the dichotomy with strange regulations and ordinances: They might seem completely nonsensical, but at the end of the day, someone decided that they were a good idea.