Four poor children try relentlessly to collect a bottle hanging from a wall that they can exchange for 0.05 yuan.

But the desperate kids, who usually collect around 20 bottles a day, were unaware the bottle was being dangled by string as part of a joke by college students, according to the Kunming Metropolitan Times.

The small kids, aged from 5 to 14, survive by collecting garbage from Yunnan Traffic Technician College in Kunming, Southwest China's Yunnan province.

One micro blog stated some students make fun of them by hanging bottles high making it difficult to reach.

People left various messages in the online comments such as, "Teachers should educate students to be compassionate before they teach them knowledge," and "Maybe the students are unaware of their behaviors may harm the children."

"The doings of the students are immoral, hurting the weakness," said an official from the college, adding that "the students involved will be criticized severely."

The children said they live in a village near the college, get up at 7 am to collect recyclable garbage, and sell them to make money. Among the children is a girl nicknamed Shasha, whose father works at the college as a cleaner and mother collects garbage.

Screenshots from a micro blog show a girl standing on the back of a boy trying to reach the bottle hung out of a two-meter-high window by some college students in Kunming, Southwest China's Yunnan province, June 20, 2012.