The Toronto Blue Jays are heading back to the American League Championship Series (ALCS) for the first time since 2016, and with more October baseball guaranteed at Rogers Centre, fans can count on one thing: more seventh-inning sing-alongs to a song that has become part of the city’s soundtrack.“I’ve written music for a hundred different series, I’ve done probably 3-4,000 commercials in my life… However, you remember this one, because it lives,” said composer Jack Lenz, who co-wrote OK Blue Jays with Tony Cosnik in 1983.What began as a lighthearted jingle has endured for more than four decades, cementing itself as the team’s unofficial anthem. Played during every seventh-inning stretch at home games, the tune has carried fans from Exhibition Stadium to Rogers Centre, through regular seasons, playoff pushes, and even World Series glory.Lenz and Cosnick’s OK Blue Jays is played in the seventh inning of every home game at Rogers Centre. Photo: CityNews.A song that wasn’t supposed to lastLenz recalls that he and Cosnik weren’t exactly baseball insiders when they were approached to write the track.“Tony and I had never been to a game; we always say we weren’t qualified to write the sports song,” Lenz said with a laugh. “But [then-team president] Paul Beeston came to our office. He was enthusiastic, but he said don’t overpromise — and then of course, OK was the idea.”The “idea” turned into a gold record. The single sold more than 50,000 copies, earning Lenz and Cosnik industry recognition in 1986. But for Lenz, the song’s legacy is measured less in sales and more in moments.He remembers taking his father, a farmer from Saskatchewan, to a game in Toronto. When the crowd rose to sing OK Blue Jays, his young son tugged on his grandfather’s hand and proudly declared, “My dad wrote that song.”“That was a big family moment, but it was also a moment where I realized he could see that I was gonna be okay,” Lenz said.From the stands to social mediaThe anthem’s staying power has reached a new generation of fans — and musicians. Max Kerman, frontman of Canadian rock band Arkells and a lifelong Blue Jays supporter, recently posted his own acoustic version of the song on TikTok after Toronto’s Game 2 ALDS win over the Yankees.“It’s become a part of the fabric of the city, of the country, this song,” Kerman said. “I was feeling very pumped after Game 2, and just before I went to bed, I was like, I’m just gonna bang out this little acoustic folksy version. It really caught on — people are feeling very festive for that song right now.”The Blue Jays advanced to the ALCS after defeating the Yankees in four games. Toronto now awaits the winner of the other Division Series between the Detroit Tigers and Seattle Mariners, with a decisive Game 5 set for Friday.Game 1 of the ALCS will be played at Rogers Centre on Sunday at 8:08 p.m. ET. One thing is certain: when the seventh inning arrives, tens of thousands of Blue Jays fans will once again rise to their feet, belting out a song that has outlasted eras, rosters, and stadiums.