"Ba ba ba, ba banana, Ba ba ba, ba banana, bananaaaa," they sing to the tune of The Beach Boys' Barbara Ann.
The silly refrain from the minions of the movie Despicable Me sums up the kind of playful fun that keeps the Hong Kong a cappella group Lasagna going.
Whether bankers, marketers or engineers, they put aside the day's work and let loose - and it's a hobby that's becoming more popular in the city.
A cappella performers sing without accompaniment. "It's not a very common type of music here in Hong Kong," said Kim Lo Yee-tak, 29, one of the founders of the six-person group.
But she said the art form is blossoming, fuelled by the success of YouTube a cappella stars such as Pentatonix. Since 2012, the Hong Kong Jockey Club has been sponsoring the International A Cappella Festival, featuring groups from the United States and Britain, as well as local talent.
It has also launched an a cappella education programme, while the Leisure and Cultural Services Department has also brought in more a cappella acts.
There are thought to be more than 20 a cappella groups in the city, mostly linked to schools and universities.
But some, like Lasagna, are more professionally oriented, entering international competitions and performing at events across China.
Lasagna reigned supreme at last year's A Cappella Championships in Singapore.
A cappella has a long tradition in American colleges and high schools, recently made more popular by television shows and movies like Glee and Pitch Perfect.
Some YouTube a cappella stars can make a living from posting videos and raking in money by allowing adverts on their page.
On Monday, Lasagna perform at the Lee Shau Kee School of Creativity in Kowloon City. Their first solo concert in February saw a full house.
The Hong Kong University of Science and Technology graduates have been going strong since meeting at a university-organised music camp in 2009.
They rehearse twice a week, but Lo said: "It's not been easy. The working culture here doesn't promote work-life balance."