Privet everyone!

I was wondering if anyone could give a concise explanation about who Мальчиш-кибальчиш is. I know that he is from a series of Soviet fairy tales, but have not yet had a chance to read them.

Could you please tell me what is probably meant when someone calls you мальчиш-кибальчиш as a nickname?

Thank you for your help!
Спасибо большое!