In the late '60s and early '70s pop songwriters, arrangers and producers, for a few years adopted the phrase "na na" as their nonsense syllable of choice for punctuating repeat choruses. Prime examples of this would be both the Cannibal and The Headhunters and Wilson Pickett versions of the hit 'Land of 1000 Dances' and 'Na Na Hey Hey Kiss Him Goodbye' by Steam, (That one even had some 'heys,' way back when), among others. There was a certain chant-like quality in those syllables that lent an anthemic, crowd rousing element to the songs.
In the past few years the prevalence of pop songs with choruses featuring some variation of a chanted 'hey' or 'hey ho' or the very successful inverting of the two in the hit by the Grammy nominated act from New Jersey, The Lumineers' 'Ho Hey.' But it has reached almost epidemic proportions. Sometimes the 'hey' is dropped altogether and just the 'ho' becomes a repeated inverse of itself- the simple 'oh' as in the Imagine Dragons hit 'Radioactive.'
Perhaps rootsy, folky banjo slinging acts can be sited as prime suspects in establishing this rampant, trendy, almost obligatory element in current pop, or maybe it can be traced back decades earlier- something from Paul McCartney and Wing's Band on the Run album, but it seems to be THE most required element in current pop since bringing in a rapper to be featured in a middle section of an otherwise mainstream top 40 type record.
The listening public tends to signal to producers and artists that they have had their fill of a trend and that it has run its course, but this one seems to have taken root and is sticking around. With numerous variations the examples of this trend are plentiful. If you think of some, maybe your favorite, or least favorite, or most annoying, feel free to it mention them in the comments area.