Here is a provided link to the hoax I found about a claim that a Hungarian song "Gloomy Sunday" that allegedly caused many suicides in Hungary and more in the United States after it was translated and re-recorded by Billie Holiday. Lyrics are provided. http://www.snopes.com/music/songs/gloomy.asp.
--Just in case you're curious, here is the link to the original, Hungarian version written by Rezso Seress and Laszo Javor in 1933: http://www.youtube.com/watch?v=4WBZwLkvpFI
--and the American version by Billie Holiday: http://www.youtube.com/watch?v=48cTUnUtzx4
More recent and modern versions have also be created.
This hoax claims that the song and lyrics caused the deaths of up to 200 people worldwide after the songs release in Hungary and translated to English by Billie Holiday in the U.S. The first questions that arise to validate this claim would be: How were the suicides linked to the song? Did the song itself cause many individuals to kill themselves, or were they linked in some other way?
Suicides were linked to the song in a variety of ways, some left suicide notes with references to lyrics, held Gloomy Sunday sheet music in their hands, or had "Gloomy Sunday" playing when they died. These claims could have been placed by some biased by the people that found them dead or they may have believed they found references to the song when there were none (confirmation bias).
Firstly, we cannot disprove or disprove this hoax because it is not falsifiable. We simply cannot bring back the dead and conduct a study to find out whether there is sufficient evidence that the song caused such emotional destruction that it led the listener to kill them self. We can only use inferences by clues left behind by the subjects.
Secondly, it is unclear whether or not the song caused the suicides, or if there was another or several other factors that influenced the person to commit. It is coincidental that many people referred to "Gloomy Sunday", but it is extremely common to have songs and lyrics referred to in the event of suicide. We could take many examples of songs and relate them to several suicides. For this reason it cannot be proven that the song is what caused the suicide. This is the most useful principle for evaluating this particular claim.
This hoax reminds me of the Judas Priest example of the alleged subliminal message in one of their songs that caused people to kill themselves.