小3你不也是个孩子么
[xiăo 3 nĭ bù yĕ shì gè hái zi me]
'Cheater, aren't you just a child too?' is an empathetic appeal to someone involved in infidelity (often referred as 'xiaosany' meaning the third party). The person tries to remind them of their youthfulness and possibly ask for understanding or leniency.