The next time you proudly sing along with the U.S. national anthem at a sporting event, take a moment to consider that it was once a song about drinking and sex. "The Star-Spangled Banner" is an example of a contrafactum—when new words are added to an old tune. Some of the most well-known songs in history, like these eight, were once vastly different than what we've come to know today.

1. "TWINKLE, TWINKLE, LITTLE STAR" // "THE ALPHABET SONG" // "BAA BAA BLACK SHEEP"

Which song was the original? None of them. The tune is based on an old French folk song called "Ah, vous dirai-je, Maman” (“Ah, Mother, If I Could Tell You”). It was already popular when a young Mozart composed Twelve Variations on "Ah! vous dirai-je, maman” in the 1780s.

The three popular children’s songs are basic versions of the tune. As for which of them came first, “Twinkle Twinkle” was originally a poem published in 1806, but doesn’t appear to have been set to “Ah! Vous dirai-je, Maman” until 1838. “The Alphabet Song” (“A-B-C-D-E-F-G”) was published as “The Schoolmaster” in 1834, and “Baa Baa Black Sheep” existed under a different melody as far back as 1744. Of the three, It seems like the first to use the French tune was probably “The Alphabet Song,” but it’s hard to say for sure.

2. "THE STAR-SPANGLED BANNER"

Though Francis Scott Key’s lyrics are unabashedly American, the tune they're set to is anything but. Before it crossed the Atlantic, “The Star-Spangled Banner” was a British song called “To Anacreon in Heaven.” Written for a London gentlemen's music club called the Anacreontic Society around 1775, the song originally celebrated Anacreon, an ancient Greek poet who enjoyed love, music, and wine.

3. "MY COUNTRY, TIS OF THEE"

The U.S. national anthem isn’t the only patriotic song to have originated elsewhere: Though “My Country, Tis of Thee” has more regal origins, its back story is similar to “The Star-Spangled Banner.” The song may have first appeared as “God Save Great George the King” sometime around 1740, and it’s still used today as “God Save the Queen/King”:

Baptist minister Samuel Francis Smith didn't match American lyrics to it until 1831, while he was studying at Andover Theological Seminary. During the 18th and 19th centuries, the song also became the Danish national anthem, the Prussian national anthem, and the Liechtenstein national anthem, among others.

4. "HARK! THE HERALD ANGELS SING"

Before “Hark! The Herald Angels Sing” was a Christmas carol celebrating the coming of the “newborn king,” it was a Felix Mendelssohn cantata that celebrated the coming of Johannes Gutenberg. Called “Festgesang zur Eröffnung der am ersten Tage der vierten Säcularfeier der Erfindung der Buchdruckerkunst,” the piece was written to honor the 400th anniversary of the invention of the printing press. In 1855, an English musician named William Cummings made a 1739 composition entitled “Hymn for Christmas Day” fit the Mendelssohn masterpiece. Today, of course, “Hark! The Herald Angels Sing” is much better known than the Gutenberg cantata.

5. "AULD LANG SYNE"

Many people hear “Auld Lang Syne” exactly once a year, when the clock strikes 12 on New Year’s Eve. In Japan, the nostalgic song is much more commonplace—it’s used in many retail stores to notify customers that the store is closing soon. Instead of “Auld Lang Syne” (which is itself a mashup of an old folk song and a Robert Burns poem), the song is called “Hotaru no Hikari,” with lyrics about the various hardships suffered by a devoted student, including studying by the light of a firefly.

6. "WHAT CHILD IS THIS?"

This religious Christmas standard has come a long way since its 16th-century origins as an old English folk song. The original lyrics sang the praises of “Lady Greensleeves”—and there’s a theory that the term “greensleeves” is actually a reference to a prostitute.

Though rumors have long swirled that Henry VIII wrote the song for Anne Boleyn, they’re probably false—the song didn’t become popular until the reign of Henry’s daughter, Elizabeth I.

7. "YANKEE DOODLE DANDY"

You’ve probably been singing "Yankee Doodle" since before you can recall—it’s one of the most common folk songs in the U.S., not to mention the state anthem of Connecticut. But before it was a Fourth of July staple, the British sang it to make fun of the poor, ragtag colonists. And before it was theirs, the Dutch used it as a harvest song, using nonsense lyrics like “Yanker dudel doodle down.''

8. "MY WAY"

Few songs are as synonymous with a performer as "My Way" is to Frank Sinatra—but it wasn't actually "his." It started out as a French song called "Comme d'habitude," written in 1967 by composers Claude François and Jacques Revaux.

Singer, songwriter, and onetime teen idol Paul Anka heard it while visiting Paris, thought there was something to it, and bought the rights. He eventually rewrote the lyrics specifically for Frank Sinatra, and the rest is history. Unfortunately, it seems Ol’ Blue Eyes got a little burned out on his hit. "He always thought that song was self-serving and self-indulgent," his daughter Tina once told the BBC.