What is "atapper"

An atapper (from atap, the Indonesian word for "roof" also called a roofer or roof surfer) is someone who rides on top of a train, particularly in Indonesia. In Indonesia the government sees them as a nuisance and embarrassment, however, residents claim that they have no choice because they cannot be late for work, and public transit efforts are beyond woefully inadequate. Most of the people who ride on top tend to be risk-seeking young males, as it is dangerous.