Officials say they received reports of a girl holding up a sign reading, "Help me, she's not my mom!! Help!!" while in the back seat of a car on Highway 99 in Stockton.
Six patrol units, including a K9 unit, made a high-risk enforcement stop but soon learned the girl had made the story up "as a fun thing to do."
CHP says the mother was unaware of the note, and officers allowed them to leave.