Spanish phrase
Esto queda entre tú y yo.
Meaning
This stays between you and me.
When to use it
It means that only two people will know something. It is used to promise privacy in a friendly, informal way.
Example dialogue
No le digas a nadie que perdí mi dibujo, ¿sí?
Do not tell anyone that I lost my drawing, okay?
Sí, esto queda entre tú y yo.
Yes, this stays between you and me.