Of course we make up words and expressions. They run in families.
Liz and her friend were driving by a wetland on a spring night. They heard lots of chirping.
“What is it that makes that noise?” the friend said.
Liz said, “Um, crickets?”
“No,” the friend said, “it’s little frogs. Crickets would never be that loud.”
“I don’t know what they’re called,” Liz said. Then, reluctantly: “Peepers?”
“Yes,” said the friend, “peepers!”
“You call them peepers, too?” Liz said. “I always thought it was just a word my ditzy mom made up.”