If you’re reading this, chances are you recently attended your first Orioles game in Baltimore and sang the national anthem expecting something different than what you heard. Don’t worry. The reaction is normal. We’re here to explain.

Out-of-towners have been caught off guard for decades by the unique wrinkle Baltimore sports fans give “The Star-Spangled Banner.” It arrives without warning or build up, ambushing the song’s 61st word, the first of its seventh line.

On the page, the lyrics read:

“Oh say does that star-spangled banner yet wave”

But for Baltimore sports fans, the words have long been sung (OK, maybe screamed) like so:

“Ohhh!!!!!!!!!! say …”

What is the story behind exaggerating the “Ohhh!!!!!!!!!!”? Where does it come from?

The short answer is: tradition. It’s important to remember the history of the anthem, written by Maryland lawyer and poet Francis Scott Key during the Battle of Baltimore in the War of 1812, while on a ship watching the bombing of Baltimore’s Fort McHenry harbor.

Connecting the rest of the dots is a straightforward exercise. Today, Camden Yards sits just four miles from Fort McHenry. “O” is short for “Oriole,” and is also a signature feature of the Baltimorean accent.

The habit of stressing one of the song’s certain syllables caught on roughly 160 years after it was written, spearheaded by legendary Orioles superfan Wild Bill Hagy in the late 1970s. Leading cheers from the upper deck at Memorial Stadium, the “Oh!” became a staple of Hagy’s “Roar from 34” routine, growing in popularity over the years. It survived both Hagy’s boycotting of Memorial Stadium in 1985 and his death in 2007.

Today, it is an expected occurrence at Baltimore Ravens football games and local college and high school sporting events, as well as Orioles games. Fans like to carry it with them, also: it’s not uncommon to hear the “Oh!” from pockets of visiting O’s fans at different parks along the Major League circuit. It even made it all the way to Brazil during the 2016 Summer Olympics, giving Baltimore native Michael Phelps a hearty chuckle before he received one of his gold medals.