人小鬼也不大
[rén xiăo guĭ yĕ bù dà]
'人小鬼也不大' roughly means: though young in age, the person is not very cunning or mischievous. The word 'ghost (鬼)' here refers not to a real ghost, but indicates tricksy behavior or naughtiness, implying the user's innocence or straightforwardness.