"Mischievous" or "naughty" are common words used to describe a playful or misbehaving child. "Rambunctious" is another word that can be used to describe a child who is energetic and prone to causing mischief. "Prankster" is another word that can be used to describe a child who enjoys playing practical jokes or pranks on others. It's important to remember that children, especially young ones, are still learning and developing, and it's normal for them to be curious and sometimes mischievous. It's important for parents and caregivers to provide guidance and boundaries to help children learn appropriate behavior and make good choices.