Blah,Blah, Blah

Like,you know,uhh,some people  I have noticed recently say "blah,blah,blah" a lot when they are relating a story  when they want to end their conversation description.  I myself uhh,you know, like uhh,like, like,uhh, never  say like "blah,blah,blah".Instead, I say "Well, whatever" or  to make a long story short".

What I wonder is how "blah,blah,blah" started and like uhh,you know, why the saying is "blah,blah,blah" and not "blah" or "blah,blah" or "blah,blah,blah,blah" or even "blah,blah,blah,blah,blah", not to mention "blah,blah,blah,blah,blah,blah"?  Well whatever,to make a long story short, does anybody out there like,uhh,you know like,like,uh like you know,you know this like uhh, reason for the "blah blah,blah'?