How to Say "Peek a Boo" in Japanese

いないいないばあ

inai-inai-bā[ina̠iːna̠iba̠ː]

To say peek a boo in Japanese, use いないいないばあ (inai-inai-bā).

いないいないばあ is said when playing with a baby, hiding your face and then suddenly showing it to make the baby react.

What does it mean word for word?

The phrase combines いないいない, meaning is not there, is not there, with ばあ, a sound for the sudden appearance.

It is read inai-inai-bā, with a long a at the end.

In some Japanese households, parents perform いないいないばあ by hiding the baby's face with a towel instead of covering their own, shifting the perspective of the disappearing act.
While いないいないばあ is for infants, the same word ばあ can be used by adults to jump out and surprise someone in a prank, acting as a general exclamation of surprise.
The phrase uses the negative form of the verb 'to exist', which creates a linguistic 'vanishing act' where the speaker literally claims to not exist before reappearing.

「わぁ、可愛い赤ちゃん。お名前は何て言うんですか？「理那よ」「理那ちゃん、いないいないばあっ！あっ、笑った。抱っこさせてもらってもいいですか？」「どうぞ」
"Aww, what a cute baby. What's her name?" "Rina." "Hey Rina, peek-a-boo! Look, she smiled. Can I hold her?" "Sure."
Someone plays いないいないばあ with a baby named Rina and she smiles.
Tatoeba #9944604 by small_snow, translation #9944614 by DJ_Saidez
いないいないばあをしよう。
Inai inai baa o shiyou.
Let's play peek-a-boo.

A young couple is playing with their baby at home.

美咲 Misaki

見て、健太さん。赤ちゃんが笑ったよ！
Mite, Kenta-san. Akachan ga waratta yo!
Look, Kenta. The baby laughed!
健太 Kenta

本当だ。いないいないばあをしたんだね。
Hontou da. Inai inai baa o shita n da ne.
You're right. You did peek-a-boo, didn't you?
美咲 Misaki

次は健太さんが、いないいないばあをして。
Tsugi wa Kenta-san ga, inai inai baa o shite.
Next, Kenta, you do peek-a-boo.
健太 Kenta

了解。いないいないばあ！
Ryoukai. Inai inai baa!
Roger that. Peek-a-boo!

Sources

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