Nicknames are made in Esperanto when you add -ĉjo to the end for males and -njo to the end for females. Therefore, Paĉjo and Panjo are affectionate terms by using this rule.
This seems weird to me. I almost all language the words for daddy and mommy are extremely simple to pronounce: English: daddy / mommy (1 consonant, 2 vowels) Spanish: mamá / papá (1 consonant, 1 vowel) Hebrew: Ima / aba (1 consonant, 1-2 vowels) Arabic: mama / baba (1 cons., 1 vowel) It's just weird to me that esperanto has a word for "daddy" with 3 consonants, one of them is actually 2 consonants joined together. A newborn would have a really hard time learning it. Why not "papo" and "papino" which makes it much simpler and still logical
My kids grew up calling us paĉjo and panjo, made it easier to find them in a crowd when they called us. The youngest is about 20 now, and they still use paĉjo and panjo when they are trying to get our attention.
It's about all the Esperanto that the younger kid knows. We weren't ready yet to raise them bilingual.
My kids (only slightly younger than Fred's) still call us Paĉjo and Panjo - often for the same reason, although they did grow up with two languages and are bilingual to varying degrees. For a while, our first child mispronounced the names and ended up calling us Papo and Mamo, respectively.