Jimmy Fallon pulled some overtime this weekend as he entertained some strangers while out to dinner.
The four-time Emmy Award winner, 47, serenaded his fellow diners with an impromptu performance of Neil Diamond's 1969 karaoke classic "Sweet Caroline" in a clip obtained by PEOPLE, taken Friday at the Polo Lounge in Beverly Hills. The festive outing marked his first time in Los Angeles since before the COVID-19 pandemic began.
"The place was so busy and there was a great atmosphere in there and there was a pianist playing, and suddenly, Jimmy just gets up and grabs the mic and starts chatting to the crowd and then singing," a source tells PEOPLE.
"He said he hadn't been in L.A. for two years and sang someone 'Happy Birthday' and did a great little performance," the insider adds. "He was wearing his mask so people didn't know it was him instantly. He was in such great spirits and everyone loved him."
He also worked the crowd with some cheeky one-liners befitting the Saturday Night Live alum, telling an elderly woman it was the "worst time to go to the bathroom" as she attempted to walk past him. "I love you guys! Be safe," Fallon told the crowd as he finished the song.
Fallon previously sang "Sweet Caroline" alongside pal Drew Barrymore in their 2005 romantic comedy Fever Pitch, as the song is a beloved tradition at Boston Red Sox games, where much of the movie was set.
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Fallon is also giving another talented singer the opportunity to perform on The Tonight Show Starring Jimmy Fallon as part of the grand prize offered on Clash of the Cover Bands, which premiered this month on E!.