For me, the title of Alfred Hitchcock's film *Dial M for Murder* is ambiguous, it may mean

* either *Dial M to order a murder* (instead of a pizza) / *for a murder to occur* (similar to the previous, but without the delivery service connotation);
* or *Dial M if a murder occurred* (it is like a police station number).

What does it really mean for native speakers, or is it deliberately obscure?