Arabs have historically been very susceptible to rumors, no matter how bizarre. (One only has to look at the many rumors about Zionist control of animals that I documented recently.) Much of the Arabic news media will happily pass on rumors as fact.Read the whole thing.
Now, Facebook and other social media tools can be used to make Arab rumor mongering much more effective.
I recently saw a rumor in an Arabic news source that there was an attempted coup in Oman a couple of weeks ago. Tracing it back, it appears to have been started on, you guessed it, Facebook: