Rancourt developed his signature fist pump - there were four on Wednesday night - in homage to former Bruins forward Randy Burridge, who played for Boston from 1985-1991. Nicknamed 'Stump', Burridge famously adopted the 'Stump Pump' as his goal celebration.
"When I saw the way that he did it, the exuberant way that he did it, I said, 'That's for me.' Just the way that I was the first time I saw a professional hockey game," said Rancourt, also known for his eccentric vest-tie combinations. "I said, 'Oh boy, this is something,' especially if I get to see it for free. It's great."
A classically trained opera singer, Rancourt estimates he has performed the anthem over 1,500 times during his 42-year run. But none of them compare to his performance on April 17, 2013.
Just two days after the Boston Marathon bombings, the Bruins returned to the ice against the Buffalo Sabres for the first major event in Boston following the attack. During an emotional and unforgettable pregame ceremony, Rancourt began the anthem before giving way to the TD Garden crowd, creating one of the most memorable moments in Boston sports history.
"Nothing comes close to that," said Rancourt. "I was petrified to get out there and I had planned to stop singing in the middle of it. I was very, very afraid of doing that, but the reaction was something that I will never, ever forget. That is my proudest memory.
"That's it. The highest moment of my singing career, and I didn't hardly sing a note, but that's life, isn't it?"
Rancourt also remembered fondly his singing of 'Auld Lang Syne' as Ray Bourque helped Normand Leveille - left unable to walk after suffering a brain aneurysm at age 19 - skate around the ice during the farewell to the Boston Garden in 1995.
"Normand Leveille, the Canadian - excellent hockey player, by the way," recalled Rancourt. "He was brought back here in uniform, and Ray Bourque and another Bruins player helped him, and they skated him down the ice as I was singing, 'old acquaintance be forgot' with tears in my eyes. So, that was another memorable moment."
Rancourt, who will be honored before the B's final home game on April 8, hopes to create a few more memorable moments before he closes things out officially at the end of this season.
"You're walking down the street and you're deep in thought, and you hear, 'O Canada,' and I'll turn and say, 'Don't quit your day job now,'" Rancourt bellowed. "It's wonderful. The fan reaction - they take their hockey very, very serious. It took me a while to learn that, but I did and it became very engrained.
"Now, every time I sing the anthem, I imagine that it's for the last time, and [Wednesday night] it was almost the last time. I imagine it's for the last time, and I try to give it all I have, and I try to prepare as much as possible.
"Each year, the preparation becomes longer and longer, so I had to make the decision. It was a tough one."