It's putting in off-beat rhythmic accents.
Not just duh - DUH - duh - DUH - duh - DUH - duh - DUH like someone banging their head against the wall.

Lots of early jazz is packed to the brim with it.
( The Mock TurtIe ™ --- Thinks you are a cunt, on, Sat 4 Jul 2009, 0:22, archived)

I like jazz.

( baldmonkey a frothy foul-smelling vaginal discharge, Sat 4 Jul 2009, 0:23, archived)

no you don't
no one likes jazz

people just pretend to like it because they're wankers
( Gilgamesh gazed in wonder as Frampton came alive, Sat 4 Jul 2009, 0:26, archived)

I like jazz cos black people are cool

(richard cropper's comedy account Stephen Frizzle is on the sex offenders list, Sat 4 Jul 2009, 0:32, archived)