[His people's culture.
Anyone other than family using that particular turn of phrase around Bumi would earn themselves a reaction ranging from snark to a fist in the mouth. Zuko is, and always will be, family.]

Old habits die hard.
But, you'll be pleased to know that baby pictures of adorable airbending children work just as well on time displaced Avatars as it does on high ranking military personnel.

[On the off chance Zuko might need that kind of thing.]