Shanghai traffic police warned on Wednesday that they will start to punish drivers who have dolls stuck to the exterior of their cars.

Such drivers will be fined 200 yuan (US$30) and have two points deducted from their licenses as such behavior “endangers the safety of others,” police said.

Dolls on cars have become a fad recently, and “Superman” or “Spider Man” stuck on top of cars can often be seen on Shanghai streets. Such dolls are usually attached with magnets or glue.

One of the sellers of the dolls on taobao.com claims that "they won’t come off, even when you drive 160 kilometers per hour or when there's heavy rain or strong wind." But Shanghai police aren't buying it.

They could impede the view of drivers, distract other drivers, and if they come off they could pose even more danger, police said.