Nǎinai mōzhe tā de tóu xiào dào: 'Zhēn shì gè xiǎoguǐtóu.'
Grandma patted his head and laughed: 'What a little mischief-maker.'
Tips
usage
小鬼头 is an affectionate or mildly scolding term for a clever, mischievous child. It is warm and playful in tone — not a genuine insult. The 鬼 (ghost/devil) element emphasises the child's craftiness or impishness rather than anything supernatural.