The lost origins of Equestrian pop music

Ever wondered why everypony in Equestria always bursts into random pop music songs? If so, It is high time you found out.

Bursting into random pop music songs has been an Equestrian tradition since the dawn of time, or maybe not...I mean somepony must have started the tradition right? Or maybe not somepony...Some siren! Who knows where she and her sisters got the idea from?

Warning: this story contains references to Greek mythology.