The "amen tic"

Recently, I was placed on a list of "frum 'n cool blogs," which I must say I found amusing, because:

1. I may be moderately observant, but only totally secular Jews would think I'm frum.

2. Pillage Idiot is far from "cool." I would say that "puerile" is a more apt description.

Anyway, I haven't davened regularly in my lifetime, so saying kaddish for my father over the past few weeks has been an interesting experience for me. As a newcomer, I can offer obnoxious recommendations. You've already read my suggestion for streamlining the shacharit service ("one-minute shacharit").

What's eating me now isn't a recommendation but a puzzling question.

At two different minyanim at which I've davened mincha, I've come across people who say "amen" during the kaddish in what is (to me, anyway) a totally bizarre manner. Instead of just saying "amen," they shout it -- bark it, really -- in a fast staccato so that the word "amen" sounds almost as if it had one syllable. (Perhaps I should have said "marcato," so that you musicians would understand better what I mean.) It's such a strange sound that after one minyan, I asked a friend who was there who that guy in the corner was with Tourette's Syndrome. It's like a tic.

So my question is this: Where does this barking practice, this amen tic, come from? Surely, these people all went to the same orthodox summer camp, right? It can't be a coincidence.