Conversation @ Lunch

Boaz: Mama, are there bad doctors?
Me: I suppose so.
Boaz: Oh...witch doctors are bad doctors.
Me: Yes, I guess so.
Asher (confused): Which doctors are bad doctors?
Me: Yes.
(Nandry starts to giggle.)
Asher (really confused): WHAT doctors are bad doctors?
Me: Witch doctors.
Asher (changing his question): Which doctors?
(Nandry laughing out loud)
Me: Yes, witch doctors.
Asher: WHAT?
Me: Which witch doctors?

Finally, after explaining using the French word "Maribou" and Baka word "Nganga", Asher gets it and keeps repeating "which witch doctors?"