The word kidnap was first recorded in 1666.
It referred to the criminal practice of enticing children or apprentices to come away and be sold to sea captains who took them to British colonies to be sold as slaves, laborers, or indentured servants.
Kid was an underworld reference to a child, while nap, a variation of nab, means to seize or steal.
Today, kidnap means to abduct either a child or an adult.
A kid is a young goat, and that is the origin of the word’s slang use for a child.
“Kidding around” is acting childish.