son: dad, how did you know i had bad grades?  father: [roflmao] son, even walls have eyes and ears
(тайное всегда становится ясным in russian)  an expression meaning  even the best kept of secrets will become known sooner or later
"son: dad, how did you know i had bad grades?  father: [roflmao] son, even walls have eyes and ears" What is the definition of "even walls have eyes and ears"?