Around 10 p.m. in Ho Chi Minh City's rapidly-gentrifying District 8, an old Honda scooter pulls up to the curb of a busy road.
Two young men get off and struggle to lift a large white box strapped to the back. Pop music starts blaring from old speakers and the younger and slimmer of the two darts between street-side tables of diners, selling tubes of peanut candy.
The older starts singing into a wireless microphone.
Brothers Nguyen Van Chieu, 22, and Nguyen Quoc Chi, 15, have been making a part-time living from this xe keo keo mobile karaoke routine for three years. In Vietnamese xe means vehicle and keo keo is the peanut candy they hawk for VND3,000 (US$0.15) apiece.
As in other corners of Asia, karaoke is wildly popular in Vietnam and singing has become big business. Vietnam Idol, a spinoff of the British and then American TV sensation, is into its third season on local television.
Vietnamese authorities periodically crack down on karaoke joints, some of which double as brothels. A few years ago they tried to ban dancing and alcohol in karaoke shops.
But bigger, gaudier and plusher establishments pop up daily.
For those who can't afford the hourly rates of karaoke bars, or prefer the music to come to them, the street busking tradition is thriving. In cities across Vietnam, guitars are being swapped for stereos on wheels and folk tunes for techno-backed pop songs.
Chieu first came to the city four years ago in search of a job. Chi quit school at grade three and plans to be a bike mechanic. They fell into busking for the money, and the music.
"I sing love songs and modern songs, whatever is popular," says Chieu, who works days in a café for VND1.2 million a month and treats this as an extra cash job.
Most nights they drive around districts on the far side of a tributary of the Saigon River that separates downtown from the rest of Saigon's fast-growing urban sprawl.
Everyone drinks beer
Before the recent construction of bridges linking them to central District 1, districts 4 and 8 were harder-to-reach working class neighborhoods. Now, thanks to proximity to the city center and a real estate boom, they are gentrifying fast.
District 4 has long had a colorful reputation, known for mafia strongmen, late night restaurants and a lively transexual community. Naturally, there's good business for Chieu and Chi.
"It's easier to make money because there are many customers and everyone drinks beer," explains Chieu as he rummages for CDs.
Nguyen Thi Ha, a mobile CD vendor who pedals a cart of pirated disks around District 8 likes to stop and listen to Chieu sing but says it won't do her sales any good.
"The songs they sing are very popular so everyone already has the disk," she says. "But I like his singing, it's good."
Rather than beg like other buskers do, they make money from selling their candy to the street-side audience. They'll earn VND80,000 for 100 pieces sold, but Chieu says if they ever sell under that amount the owner of their bike and music box rig will pay them nothing for the night.
Candy sales are only source of income. The best money is made from the drunk, who often prefer to sing rather than listen.
At about 11 p.m., the brothers stop in Binh Chanh District, one of the city's farther areas beyond District 8, beside a street-side seafood vendor where a table of seven requests the mic.
Chieu sets up the song. Chi hands over the microphone. The diners take turns singing an old ballad called Mua dong khong lanh (The winter is not cold), as Chi makes rounds of the table, selling over 10 pieces of candy.
One singer, Trang Quang Vinh, 22, says karaoke motorbikes have been around for about 10 years. "I sing about once a week. It's fun and a good way to unwind along with my beer buddies."
By midnight, the brothers have made their way to another part of town onto a side street of brightly-lit late night restaurants, still churning through the same song about winter.
If it looks like they might not make their target Chi usually starts twisting arms.
"I persuade them. I'll say: 'Tonight I sold just a little so can you buy some more,'" he says. But tonight they've sold 110 pieces of candy so they'll earn their VND40,000 each.
After a few songs are sung and some more candy sold, they get back on the bike and continue down the road.