Songfacts®:

• One of the hottest jams of 2000 was "Country Grammar," with a melody based on a playground clapping song. That "I'm goin down down baby..." refrain comes from a song called "Roller Coaster," which goes:
  
  Down down baby
  Down by the roller coaster
  
  Nelly heard some little girls singing it while playing patty cake, and it stuck in his head. When his producer Jason Epperson (Jay E) played him the beat, Nelly remembered the tune and used it as the hook.
• Nelly (born Cornell Haynes Jr.) had an itinerant childhood, moving to Spain and then to St. Louis, Missouri. His music career started when he formed a rap group called St. Lunatics in 1996. They got a smattering of local airplay with their 1997 single "Gimmie What U Got" but eventually caught the ear of an executive from Universal Music named Kevin Law, who signed the group but also signed Nelly as a solo artist, making him the priority. This country-meets-hip-hop tune was Nelly's debut solo single. The following year, St. Lunatics released their debut album, Free City.
• The "shimmy shimmy ko-ko-pop" line comes from a 1959 hit by Little Anthony & the Imperials called "Shimmy, Shimmy, Ko-Ko-Bop." That song is about a dance, but Nelly gave it another meaning, transforming into:
  
  Shimmy shimmy cocoa ko-ko-pop, listen to me now
  Light it up and take a puff, pass it to me now
• The "country grammar" is Nelly's flow, which is laid-back and melodic. St. Louis is a major city but because it's in the Midwest, many consider it "country." And in the world of hip-hop, it was the hinterlands, as no big rap acts emerged from there until Nelly came along. "People think we live on farms in St. Louis, even though we live in an urban environment like everyone else," he told the Baltimore City Paper. "So we said, 'OK, you want to call us country, this is how we're going to do it.' We turned it around on them. We showed them we have our own way of talking here, our own way of making hip-hop."
• The song is a celebration of St. Louis, with Nelly rapping about his come-up in the city and how he's finally made it big. The video, directed by Marc Klasfeld, is a big block party, showing lots of people dancing to the song and having a good time. It got loads of airplay on BET and MTV.
• Nelly talked about making this song in an interview with XXL magazine: "It was a beat that I had got from one of our producers at the time JE. I loved the beat but I don't think everybody in the group was as excited about the beat as I was. So I took it to one of the most historic clubs in [East] St. Louis. It was called Club Casino. I took it over there the same night and we had a DJ that had been supporting us previously up to that point and his name was DJ 618. He put it on right away and from that moment, you know what I'm saying, people was like, 'Boom, boom, boom' and the s--t just blew up from there, you know."
• A radio-friendly version was also recorded, in which the word "s--t" is backmasked and most of the explicit words are replaced by cleaner versions and/or bleep-related sound effects.
• The album, also titled Country Grammar, went to #1 in the US and stayed there for five weeks. It eventually sold over 10 million copies there, earning the rare Diamond certification.
• Donald Trump gets a mention in the lyric along with Bill Gates as Nelly says, "Let me in now!"
  
  At the time, Trump was best known for being a rich guy, so Nelly namechecked him along with Bill Gates to signify the ultra-wealthy club he was looking to join.
• Nelly's country grammar served him well. He went on to team with some of the biggest stars in country music, collaborating with Tim McGraw on "Over and Over" in 2004 and jumping on a remix of the 2012 Florida Georgia Line hit "Cruise." In 2021 he released his own country album called Heartland.