My mother tells stories about me learning to talk.
"You would play under the table while your father and I and friends would play poker. One night someone said, "Goddamn it to hell!" and you said it right back. So your first words were "Goddamn it to hell!"
My parents also had a phrase that they would say to me. "Say "Ontogeny recapitulates phylogeny." Any baby will try to parrot back any phrase that seems important or is used often. So I learned to say "Ontogeny recapitulates phylogeny." Though it doesn't, that idea is out of fashion.
My husband and I also had a phrase for the extroverted feeler. "Say Australopithecus.", we'd say. So he learned to say "Australopithecus" very young and soon wanted to know what it meant. And asked about it when we went to the cliff dwellings.
My daughter introverted thinker learned the alphabet song.... wrong. That is, she would sing: "abcd efg hikj--". Adults would stop her and sing the alphabet song correctly. My small daughter would put her two fingers in her mouth and listen as the adult sang the song. Her eyes twinkled. It was like magic, how she could induce any adult that she met to sing the alphabet song to her....
My parents instituted a swear jar when my sister and I were little. Any person catching any other person swearing could say "Penny!" and the swearer would have to pay up. My sister and I quit using THOSE words in the adults' hearing immediately. We earned money from our parents and guests at a nice rate. However, there were times when we couldn't earn money. If my mother was driving and had a scare and swore, she would yell at us if we said "Penny!" So in the back seat we'd look at each other and mouth, "PENNY!"
My other first word was "Gog!" My mother was in the small house in Knoxville, Tennessee and heard me on the porch. I was saying "Gog! Gog!" in distress. She went to the door. The evil neighbor dog had my teddy bear and was taking it next door. She rescued my bear and shut the gate on the evil gog.