In some interpretations of Sunni law—some 90% of Muslims worldwide are Sunnis rather than Shiites—it is permissible for a man to divorce his wife by saying "talaaq" (divorce) three times. There are various rules about how far apart the talaaqs have to be or how many witnesses there need to be, and there is considerable debate about whether triple talaaq has an sanction in the foundational texts of Islam. The practice is formally banned in a lot of majority Sunni countries, and is unrecognised by (secular) Indian courts, but every once in a while a case comes up that is equal measures tragic and hilarious.
In 2006, we had the sleeping talaaq controversy, in which a man in Bengal happened to divorce his wife by mumbling talaaq in his sleep. Local religious leaders pronounced the marriage dissolved but national bodies like the All India Muslim Personal Law Board argued for sense—as much sense as there can be under the risible circumstances of instant, one-sided divorce—in that saying talaaq has to be intentional.
Today talaaq is back in the news because a cleric in Deoband, a place in India famous for its conservative brand of Islamic thinking, issued a fatwa (a religious decision) that if a man divorces his wife by mobile phone and she doesn't hear talaaq three times because of network problems, the divorce is still valid. Yikes. Without entering into the moral or philosophical questions, I find this the worst kind of simplistic application of religious law to modern technology.