well, when 7, my children didn't coin any words-- but at 4 my daughter introduced to the family a new, and still used (in our family at any rate) expression.

Her brother was showing off his newly learned ability to write real words and sentences (he was in 1st grade) Emily filled a page with squiggles, and showed it off, only to be told it was just "scribble scabble"-- she indignately held her head up, and said "no its not, Its toy script!" and so we now have toy script in our house. it is very discriptive, and simple. and sound so much less like a put down. So kids don't scribble in our family-- but sometimes they make toy script!