The 34-year-old Mandopop star got everyone "stunned like vegetable" when he invited local actor Chen Tianwen on stage to perform the latter's viral hit song Unbelievable together mid-way through the three-hour gig.
When Chen appeared, holding a head of broccoli and togged out in the retro wig and outfit from the music video, the crowd broke into frenzied applause, whipping out their cameras and phones to record the performance.
Chen's Unbelievable music video was released in April to promote Channel 5 comedy series Spouse For House 2 which he starred in, and has chalked up more than 3.2 million views on YouTube and Facebook.
Lin said on stage: "This song is famous worldwide, even making it to news in America. His song is so popular now, I am looking forward to his next song."
Chen, 52, told The New Paper afterwards that he received Lin's invitation two months ago.
He added: "It's fantastic, it's the first time I get to perform on such a big stage to so many people. Plus, JJ is an international singer with so many fans."
Indeed, many of Lin's fans found the Unbelievable duet to be the most unforgettable.
After all, his previous guest stars in other cities have included A-list pop stars such as Selina Jen from popular Taiwanese girl group S.H.E and Japanese singer Ayumi Hamasaki.
Mr Yang Quan Xiang, who works in the oil and gas industry, told TNP: "I found Chen Tianwen's appearance most unexpected, as no one would associate him with JJ Lin.
"I felt very high (happy) when he came on stage, as I could relate to the song and sing along to it."
The 32-year-old added: "It is a nice addition to the entire concert, which was already very, very good." Here are some of the show's other highlights...
Lin kept the surprises coming, performing a touching duet of his Mandarin song Japanese Rose In My Palm with his mother.
He followed that up by extending an impromptu invitation to his father and elder brother Eugene Lim, who also went on stage to sing veteran Taiwanese singer Jonathan Lee's Hills and Lin's Fly Back In Time with him respectively.
The heartwarming performance drew deafening cheers from his fans, who lapped it all up.
Miss Tan Meishan, a 29-year-old accountant, said: "I found it very touching. It's very rare for singers to invite their family on stage together, and it's quite amazing that his whole family can sing so well. Good genes indeed."
MARRIAGE ON HIS MIND
The eligible bachelor, who was formerly romantically linked to Taiwanese actress Jean Kao and Taiwanese model Lillian Chen, talked about settling down several times on stage.
He said: "When I see my friends getting married and having children, I wonder when it'll be my turn."
He added that his parents have been asking him to work less and focus more on starting a family, before teasing his fans: "Will I find a wife in Singapore?"
His constant mentions of finding a spouse led his female fans to scream in unison: "We can be your wives!"
At some point, one shouted audibly: "I want to have your baby!"
That bold declaration made a shy Lin blush as he covered his face and smiled coyly.
Lin kicked off the Timeline: Genesis World Tour - in support of his 2014 album Genesis - in Taipei on Valentine's Day and has held about 37 gigs prior to his Singapore leg.
He said: "It feels good to be back home, especially with my family and my friends watching me from the audience."
With that, he broke into this year's National Day Parade song, Our Singapore, with his local fans singing along.
This article was first published on September 7, 2015.
Get The New Paper for more stories.