The White House was tinted green on Thursday, when President Joe Biden — Secret Service code name: Celtic — welcomed “Coach Joe” Mazzulla and the Boston Celtics to the South Lawn to celebrate the franchise’s unprecedented 18th NBA championship.

In a tradition believed to have begun when Bill Russell’s 1963 Celtics met with President John F. Kennedy, Biden welcomed the NBA’s 2024 champions and gave them a tour of the Oval Office. In all, the league’s most-decorated franchise has won at least one title in eight of the last 13 presidential administrations.

“The Celtics aren’t just a basketball team. They’re a way of life,” Biden told the crowd, quoting Celtics patriarch Red Auerbach before receiving a No. 46 jersey from All-Star Jayson Tatum and guard Derrick White.

Biden noted that his Secret Service code name is “Celtic.”

“For real. Because I’m Irish,” the president said. “Everybody behind me is Irish in their heart. I feel a special pride in this trophy. From this old Irish Celtic, to all you Celtics, congratulations.”

Biden, who was once one of the youngest senators in U.S. history and is now the country’s oldest president ever, said he felt a kinship with Mazzulla, who was 35 when he led the Celtics to the title in his second season.

“Joe’s the youngest head coach to win a title since the great Bill Russell,” Biden said. “I told him I used to be the youngest and now I’m the oldest. I liked being the youngest better.” 

The Celtics were greeted with a band playing “Shipping up to Boston,” before Biden and team owner Wyc Grousbeck joined them on the risers facing the Washington Monument; green lights shined from from the eaves of the White House behind them. Among those in attendance were Massachusetts Gov. Maura Healey, Boston Mayor Michelle Wu and most of the state’s congressional delegation.

“I didn’t really know what to expect. I walked in, I was like ‘I’m more excited than I thought I was going be,” White told reporters afterward. “To be in the White House, to be where all the decisions — all the cool things — are happening, that was the best part.”