Paano pag sinabihan ka ng anak mo na "you're bad mommy ! "You're bad daddy ! How do you handle this situation ?

I guess it depends on the context of the situation, and inflection of the child's voice. Is he/she saying it in a joking manner? Or is he/she trying to use the word "bad" in a way that makes you uncomfortable? In any case, you could always encourage your little one to use a different word. Just be sure to not empower the word "bad" by implying that it shouldn't be used in that way. Simply suggest that that's not the right word for the situation and teach them an alternative...like "silly" or something like that.