The phrase “daddy daddy do” doesn’t have a widely recognized meaning in English and can vary based on context. It could be part of a playful or affectionate expression, possibly used by children when referring to their fathers.
In some contexts, it might also appear in songs, poems, or playful banter. If you have a specific context in mind, such as a song lyric or a particular situation, please provide more details, and I can offer a more accurate interpretation!