I decided to look this up and foun that the game does exist. It's called Cucu-Trás. It's identical to the basic Peek-a-boo where you cover your face and then say Peek-a-boo when you open your hands like doors to your face. For Spanish, you say cucú when your hands are covered and tras when they are opened. Similar to Peek-a-boo, you can play the game with other objects covering your face.
My son has been playing this game now for quite some time. Tonight was the first time he initiated the game in the car at night time. He's started the game before and even in the car, just never at night. He was so giggly last night. We played for at least 15-20 minutes straight. He used his blanket to cover his face and then pulled the blanket down and I would say Peek-a-boo or boo.
Now that I know the Spanish version, I'll incorporate that into his play time too.
This is typically the first game we all play as kids. It's an educational game for the babies. They really learn this as their first game often. It teaches them that its ok to be silly and it teaches them to move their hands and over objects. It also teaches a little make believe as they duck behind a small object and we all pretend that we can't see them. It teaches sounds.
I would use this to teach a little culture so that my students knew what the game was for Spanish speakers. It's important to not only learn a language, but to also learn the culture if the native speakers.
Here is a version of the game in Spanish: http://www.crecerfeliz.es/El-bebe/Psico-desarrollo/Juegos-de-bebes. (For English speakers, note the position of the hands of the dad.)