How old do you have to be for kids boop?

The term "kids boop" is not widely recognized or defined, so it's unclear what specific activity or context you are referring to. If you mean a playful or light-hearted interaction between children, it generally depends on the individual child's maturity and social skills rather than a specific age. It's important for any activity involving children to be appropriate for their developmental stage and to be supervised by adults when necessary.