Your friend didn't create "chiz" unless they're a very old friend. It came to prominence in the Molesworth books of Willans and Searle in the 1950s. Molesworth uses it as a sentence-final particle indicating "drat, curses", as in (I'm making this up, not quoting):
The master hav confiscated my conker chiz.

In extreme circumstances it may be doubled or tripled, as in (again made up, but gives the flavour):
All the new bugs dance around me saing go on molesworth you will enjoy it if you try and eventually i find myself joining in chiz chiz chiz.

On its first occurrence it is footnoted as
A chiz is a swiz or swindle as any fule kno.