After the Republican debate on Feb. 25, former presidential candidate Ben Carson faced possibly the most difficult question of his short political career.

“I’ve got to ask you to complete this sentence: If Young Metro doesn’t trust you …?” a reporter for the hip-hop and youth culture publication Complex asked the retired brain surgeon.

“Then you probably need to either become honest or be able to explain, uh, the reason for their doubts,” he replied slowly (OK, so nothing new).

It’s doubtful anyone was expecting 64-year-old Carson to know Atlanta rap producer Metro Boomin’s signature soundbite, which features frequent collaborator Future proclaiming “If Young Metro don’t trust you, I’ma shoot you.” But if the question proves anything, it’s the cultural significance of producer tags ­— audio watermarks that tell listeners who created the beats their favorite rappers are spitting on.

In fact, Metro Boomin’s tag might be the most recognizable thing about him. The 22-year-old trap producer, born Leland Wayne, has spent the entirety of his adulthood working behind the scenes with some of rap’s biggest names: Future, Drake, Young Thug, Kanye West and more. But after his “If Young Metro” tag was featured prominently on Future and Drake’s smash “Jumpman” and more recently on Kanye West’s “Father Stretch My Hands Pt. 1,” his profile has jumped over both Yeezy and Jumpman.

Twitter memes and videos featuring the phrase frequently rack up thousands of retweets, taking the Internet by storm faster than rappers flow over Metro’s beats. But perhaps the strangest thing about the tag’s meme-y popularity is that it took until 2016 for the public to latch onto a small piece of hip-hop culture that’s been there for decades.

The idea behind the producer tag is an incredibly simple one: It tells you who produced the track, a useful tool for the musicians whose contributions to songs are often overshadowed by the rappers who take front and center. Painters often sign their art, writers get bylines, and rap producers put short audio clips at the beginning of their beats.

One of the earliest adopters of the producer tags was legendary beatmaker Just Blaze, whose enthusiastic shout of his name has graced everything from the trunk-rattling bounce of Joe Budden’s 2003 hit “Pump It Up” to Drake’s moody and majestic Take Care cut “Lord Knows.”

In a 2010 interview with Grind Music Radio, Just Blaze talked about the first time his name appeared on a track: Cam’Ron’s “Oh Boy.”

“My name had been on records before but it was the first time you had heard it just loud and clear, like right at the top of the record,” he said. “It kind of set a little bit of a precedent for putting my name on the record.”

But since “Oh Boy” was released in 2002, the producer tag hasn’t just risen in popularity — it’s become a staple of modern rap music.

In part, this continued popularity is due to the rise of Atlanta trap ­— its aggressive synthesizer and 808-driven beats are produced by a scene of exciting up-and-comers, almost all of whom use distinct, recognizable name drops.

If you’ve heard any popular rap song in the past year, there’s a good chance you’ve heard a beat by one of Atlanta’s resident hitmakers — and their tag.

From Metro Boomin’s forays onto the Billboard charts to Atlanta superproducer Mike Will Made It’s work on songs by party-starting youngsters Rae Sremmurd and established pop disaster Miley Cyrus, producer watermarks are becoming nearly as common as commercials on mainstream radio. Who could forget the brief period of time when pop hits with a well-placed “Mustard on the beat, hoe” seemed to outnumber those without?

While they’ve certainly leaked into the pop stratosphere, these soundbites also remain an integral part of the street-level rap experience, as the tags of hot-commodity producers such as Southside and Dun Deal pepper the many mixtapes that rack up thousands of plays online every day. In fact, many would-be rappers are perfectly willing to dish out thousands of dollars for the privilege of placing a tag-toting banger on their next mixtape (available on DatPiff, probably).

But for the beatmakers whose names they boast, these tags continue to serve the purpose they have since their earliest uses: to give the people responsible for the instrumentals you nod your head to a little bit of the credit they deserve. Because — to paraphrase Metro Boomin’s other tag — they want some more.