In Indonesia, a particular scam is calling people (esp. parents) very early in the morning, when people are still sleeping, "We're cops. Your son/daughter is arrested for drugs possession. Send us lots of money NOW or we'll send him/her to jail." followed by what sounds like someone crying in the background.
Since you're barely awake, and your son/daughter is indeed away (eg. on night shift or staying with friends), and the fact that some cops are corrupt, and somehow you can't call (busy line) your son/daughter to verify, make people fall prey to this scam.
The interesting part is: how do they know the relationship of the victims, and the location (i.e away from home) at that point in time, considering the scammers are sometimes from different island?