Prank toys are becoming increasingly popular among city youth, and one of the popular ones these days is an "electrocuting" ballpoint pen.
Thanh Binh, a ninth grader, is proud of his pen. It looks like a normal ball-point pen but it gives the unsuspecting user a mild electric shock when the head of the pen is pressed to write.
The pen contains a 1.5 Volt battery which generates the electric current.
Binh said other "electrocuting" gadgets available include USBs, boxes of candy, flashlights and lighters.
"These days, this shocking stuff is the mode. All my friends like them and bring them to play with each other for fun," he said.
Binh said he ordered the pen on the Internet after seeing an ad. "You can go to websites and they're full of stuff like this. You can buy whatever you want."
An ad on holytoy.net says: "This is a ball-point pen that functions like other ball-point pens, plus a special use. Just give the pen to your friends. When they press the head of the pen to write, they will immediately get an electric shock. It will stun them, make them shout and even jump up!"
The online advertisements sell the items at VND50,000-70,000 (US$2.62-3.66) apiece and give out phone numbers that people can call to place orders, Binh said.
Holytoy.net recommends keeping the pen on the desk, in the bag or in the shirt pocket because, "the electric current has small intensity, so you can be sure it is absolutely harmless."
Hieu Thanh, owner of a "freak" toy shop in the city, said: "I think there would be no effect as the electric current is only 30 milliamps, not enough to harm users."
But doctors say such toys can be dangerous.
The electric shock would stop the heart for several seconds and playing with it frequently can cause mental trauma and complications to the brain, they warned.
Thanh said the pen and other similar toys came from China.
"Recently, they have become a trend among young people. They've called to order many of them and sometimes I run out of stock," he said.