The superstition that played a major role in Sarah Jessica Parker's new fashion collection

Aside from that very public spat with Kim Cattrall, Sarah Jessica Parker has led a pretty charmed life: a successful acting career for decades, a 20-year-plus marriage, three “curious” kids, a shoe and handbag line, and now, a limited-edition collection for Gap. Perhaps her good luck can be traced back to a superstition she’s been feeding since her 20s.

The Divorce and Sex and the City star’s Gap collection went on sale today. The pieces, which are colorful and cute, are part of a “love, luck, and magic” theme. At the end of the video displaying the collection, she pops up to say, “Rabbit, rabbit,” before spinning and walking away, showcasing a jacket with those very words embroidered across the back, along with images of two bunnies.

If you follow her on Instagram, where she does the majority of her social sharing, you’ve known for years about her “rabbit, rabbit” superstition. On the first of every month — before uttering any other words — she says it, and she has been doing posts around the motto to share with her fans. Sometimes she says it, sometimes she writes it, and other times she shows a bunny or two. Here are a few, from today’s to several months back.

While promoting the line, which includes pieces for women and kids, she talked about how she became hooked on the superstition. “I don’t remember who told me that saying ‘rabbit, rabbit’ on the first of the month would bring luck,” she told InStyle. “Some people say ‘white rabbit.’ Some people say ‘white rabbit,’ and then they pinch somebody — or they get pinched. There’s a lot of variations.”

She continued, “I’ve been saying it for 25 or easily more years. … I’m pretty dedicated and vigilant about it. And it’s been one of the more enjoyable parts of social media. People shared with me that they’ve either learned it from me or it reminds them of a tradition they used to do.”

Sarah Jessica talks superstitions here:

Parker shared her “rabbit, rabbit” rules for the uninitiated. “If you’re awake a midnight, you say not a word… I wait until 12:01 officially … for sure on a clock that is not self-wound, then you say it. That sort of takes care of your monthly ‘rabbit, rabbit.’ If you choose to ignore the midnight, and you can, and you must do it when you wake up, before you say another word to anybody else, [say it].” However, she admitted, “It’s very rare that I forget to say it.”

Needless to say, Parker is hardcore about the whole thing. To find out more about the history and use of the saying, Yahoo Lifestyle questioned Martha Barnette, co-host of A Way With Words, a public radio show and podcast about language.

“Rabbits have been associated with luck, both good and bad, for more than 2,000 years,” Barnette tells Yahoo Lifestyle. “It’s unclear why people started saying it for luck, and it’s not until the early 1900s that we see written examples of this practice. There are lots of variations: Some people just say ‘rabbits’; others say ‘white rabbits,’ and still others say ‘bunny, bunny.’ But the idea is the same: The first word out of your mouth on the first day of the month has to refer to rabbits.”

She noted some of the other well-known people, who have adopted the superstition. “FDR carried a rabbit’s foot for luck during the 1932 presidential campaign and supposedly said ‘rabbit, rabbit’ on the first day of the month. Saturday Night Live comedian Gilda Radner said bunny, bunny,” and the writer Simon Winchester supposedly had a streak of 696 months before he forgot to say his own version, which is “white rabbits.” She added that people who grew up watching Nickelodeon may remember the network reminding viewers to say “rabbit, rabbit” on what it called “Rabbit Rabbit Days.”

Barnette noted that if a person does forget to say it first thing on the first of the month, all hope isn’t lost. “Supposedly … you can counter any bad luck by saying “black rabbit” right before you fall asleep [that night] — or ‘rabbit, rabbit’ spelled backwards, ‘tibbar, tibbar,'” she says. “Does that fix things? Probably as much as saying it correctly in the morning brings you luck.”

We also consulted some superstition experts to see how this superstition stacks up against, say, walking under a ladder or having a black cat cross your path.

“Rabbits are ancient and widespread symbols of fertility. Reproductive success is a measure of great power in many cultures. That’s what makes rabbits ‘lucky,’” says Phillips Stevens Jr., PhD, who’s the faculty expert on superstition at University at Buffalo, SUNY. “Note the pagan symbols of Easter — rabbits carrying eggs. The old rabbit’s foot, before PETA, was a popular good luck charm — a piece of the very creature, transmitting some of that power to the bearer. Words are symbols. Words for things take on the essence of the things, so the word for rabbit becomes powerful too. Saying it twice doubles the power.”

Though Rob Weiner, who is a popular culture and humanities expert at Texas Tech University, isn’t sure quite how powerful it is. “People around the world often believe that saying certain words or having specific charms can affect their fate in some way. Words and objects can be powerful motivators if you believe they have that power.” He added: “I don’t know, however, if these kinds of superstitions have any scientific validity — it’s the power of suggestion and belief that this has the ability to change one’s surroundings.”

So will incorporating “rabbit, rabbit” sell clothes for SJP? We shall see. Because, while certainly adorable, the use of “rabbit, rabbit” in this case all comes down to dollars and cents.

Read more from Yahoo Lifestyle:

• Is Walmart selling chic clothes now?

• The history of women wearing pants as a power symbol

• The key bag trends and styles to know for fall 2018

Follow us on Instagram, Facebook, and Twitter for nonstop inspiration delivered fresh to your feed, every day.