My grandmother uses the words “Whim-wham for a mustard mill” to mean that a child is excitable and doesn’t sit still. The only other use of it on the internet says that it means something that is unidentifiable.

There is a similar saying on the internet: “Whim-wham for a goose’s bridle” that appears to be much more widespread but was used as the answer to an unwanted question:

“What ya’ doing?”
“I’m making a whim-wham for a goose’s bridle.”

Have any of you heard the earlier saying? I posted it here just so that it would be preserved as no-one I speak to has heard the saying except this guy.