Inception: Hollywood's distinctive foghorn sound 

Everyone knows movies have stylistic trends. This goes back to the early days of cinema, when no comedy was complete unless someone's face received a generous helping of flying pie. Looking back, certain stylistic cliches can be spotted which almost date them. Your movie is set in a remote jungle? The opening sequence must have a low fly over shot. Your action thriller must have the hero being beaten up, and only winning through when all hope seems lost.

Technology plays a role too. Once some gimmick is tried once, and seen to catch on, it seems to be everywhere and usually gets it's name from the first time it was used. There's an example of this with the loud, dramatic, pounding, repeating sound that directors just can't seem to stay away from, and it's known affectionately as the "Inception Foghorn". The problem? It's not in the movie. At all.

District 9

The first time the "Inception Foghorn" was used was the movie District 9. It's since appeared in countless others, including Prometheus.

A possible explanation for the way the name stuck could be from the trailers for the Inception movie, wherre it certainly is present, but it's easy to find others where it appeared before. There's a great piece covering this here, where the sound has been coined as "braaams" :-)