Reduplication

Reduplication, a characteristic "trick" of English, is making pairs of rhyming words. There are basically two types, those that keep the same vowel, as in super-duper and those that modify one of them, as in zig-zag. It has been used for centuries, typically in nursery rhymes, for example, but many other instances exist. Shakespeare used several, including hurly-burly. Dilly-dally was in use by the beginning of the 17th century. Argle-bargle was used by Stevenson in Kidnapped (1886) )

No vowel change

 * argle-bargle
 * argy-bargy
 * bye-bye
 * fuddy-duddy
 * hanky-panky
 * helter-skelter
 * hoity-toity
 * hurly-burly
 * itsy-bitsy
 * namby-pamby
 * oogly-boogly
 * super-super
 * willy-nilly

Vowel change

 * chit-chat
 * criss-cross
 * dilly-dally
 * knick-knack
 * pitter-patter
 * riff-raff
 * see-saw
 * shilly-shally
 * sing-song
 * tick-tock
 * wishy-washy
 * zig-zag