Some things about weddings change — like their rapidly rising cost — but some things stay the same — like time-honored wedding traditions.

What you may not know is that a lot of these wedding traditions, from the silly to the sweet, are actually rooted in superstition.

They're perpetuated by pop culture depictions of weddings in TV, film, songs. And you see them in the real-life weddings of celebrity couples. Let's take a closer look at seven of the most popular ones.

1. The bridesmaid superstition.

Folklore says that we have bridesmaids because they protect the bride from being snatched away, according to Snopes. And if you're a bridesmaid, you have your own set of wedding superstitions to deal with. For example, if you trip while walking down the aisle, you are "fated to be a spinster," Snopes said. And if you're a bridesmaid three times, you're never going to marry. Gee, thanks folklore!

Ever wonder where the tired phrase "Always a bridesmaid, never a bride" comes from? How about an ad for mouthwash? Seriously.

Listerine/AdvertisingAge - adage.com

Where you've seen it in pop culture:

Pretty much in any film or TV show that depicts a wedding, and obviously in "Bridesmaids." The movie "27 Dresses" was based on the idea of a woman who was often a bridesmaid but never a bride.

2. The "don't see the bride in her dress before the wedding" superstition.

We've all heard that it's bad luck for the groom to see the bride in her dress before the wedding. But why? It comes from the fear that the groom will think the bride is too ugly to marry and run away. When arranged marriages used to be more common, a couple was forbidden to even meet before the big day, according to Bridal Guide. To keep the bride from shaming her family by offending her groom, the bride and groom were kept apart. A veil was added for good measure.

Romance! The good news is that you no longer have to worry about bad luck if you see each other before the ceremony.

Where you've seen it in pop culture:

Every couple that married in "How I Met Your Mother" had the moment where the groom saw the bride in her dress before the wedding — with poor results.

3. The month of May superstition.

Tradition says that May is the unluckiest month for weddings, Snopes said. This dates back to Roman times: Apparently, the Romans made offerings to the dead in May. (For some Catholics, it's also considered back luck to get married during Lent.)

And that's not all! It's also bad luck to wed on certain days, like Dec. 28. If you really feel like having a chuckle, here's an old poem on when and when not to get married, lest your husband die (via Snopes):

"Married in January's hoar and rime,
Widowed you'll be before your prime.

Married in February's sleepy weather,
Life you'll tread in time together.

Married when March winds shrill and roar,
Your home will be on a distant shore.

Married beneath April's changing skies,
A checkered path before you lies.

Married when bees over May blossoms flit,
Strangers around your board will sit.

Married in the month of roses — June,
Life will be one long honeymoon.

Married in July with flowers ablaze,
Bittersweet memories on after days.

Married in August's heat and drowse,
Lover and friend in your chosen spouse.

Married in September's golden glow,
Smooth and serene your life will go.

Married when leaves in October thin,
Toil and hardship for you gain.

Married in veils of November mist,
Fortune your wedding ring has kissed.

Married in days of December cheer,
Love's star shines brighter from year to year."

Hilarious!

Where you've seen it in pop culture:

Pop culture's royal couple, Kim Kardashian and Kanye West, paid no heed to the "don't marry in May" superstition when they wed in May 2014.

4. The little black dress superstition.

The tradition is that a female wedding guest shouldn't wear a black dress to a wedding because it's considered bad luck. In many cultures, black is a color typically reserved for mourning.

As with many wedding superstitions, the tide has turned on this one. StyleCaster is one of several authorities suggesting that a black dress is perfectly acceptable wedding attire. "The goal [of a wedding guest] is to look sleek and appropriate, not over the top or high drama," Molly Guy, founder and creative director behind bridal boutique Stone Fox Bride, told SyleCaster. "Black is always a safe option. It’s good for cocktail attire, black tie, or even a mid-afternoon garden soiree."

There's even a growing trend of brides choosing to wear black wedding dresses.

Where you've seen it in pop culture:

Actress/singer Lucy Hale released the song "My Little Black Wedding Dress" in 2014. And Kim Kardashian again ignored a wedding superstition when she wore a black dress to a friend's wedding in 2016.

5. The groom carrying the bride over the threshold superstition.

This tradition may stem from the belief that evil spirits are out to ruin your wedding day. Nonspecific "ancient cultures" supposedly believed that brides were most excellent at attracting evil spirits, who would enter through the soles of their feet, necessitating the groom to carry her, according to Bridal Guide.

Another theory is that the tradition comes from the ancient Romans, who believed that brides needed to be carried because if they tripped, it was bad luck, according to How Stuff Works.

Where you've seen it in pop culture:

In "Just Married," new groom Ashton Kutcher attempted to hoist his bride, Brittany Murphy, over the threshold but managed instead to slam her head against the door frame.

6. The "something old, something new, something borrowed, something blue" superstition.

You've likely heard the saying advising brides on their wedding day accessories, which are meant to bring good luck. "Something old" represents "the bride's past"; "something new" represents the "couple's happy future"; "something borrowed" should come from "someone who is happily married in the hope that some of that person's good fortune rubs off on her," according to Martha Stewart Weddings.

And the "something blue"? It represents "fidelity and love," according to Martha Stewart Weddings.

The source of the tradition may be an Old English rhyme, which describes "something blue" (usually a garter) as a "device to baffle the evil eye," according to historians Joseph Jacobs, Alfred Trübner, and Arthur Robinson Wright, writing in "Folklore," which was published way back in the 1890s. Yup, we're back to dealing with evil spirits.

The old poem also advises that a bride carry "a silver sixpence in her shoe" in hopes of good fortune.

Where you've seen it in pop culture:

Many TV shows, including "Friends," "How I Met Your Mother," and "Grey's Anatomy," use this trope. It is also shown in "The Simpsons," where Lisa's "something blue" is a lock of Marge's hair.

7. Rain on your wedding day superstition.

In many cultures, rain on your wedding day means a marriage full of good luck. A Hindu belief is that rain on your wedding day is a sign of unity, according to The Pink Bride. In other cultures, rain is a sign of fertility. For others, it's a symbol of cleansing.

Where you've seen it in pop culture:

Alanis Morissette's 1996 smash hit song, "Ironic," featured the lyric "It's like rain on your wedding day," which, as many have pointed out, is really in no way an example of irony.

No.