A Lalu and wife moved in a new housing colony where all houses looked alike. Drinking Lalu would come home late from socialization at the Bar, would not figure out which house to go and end up disturbing neighbors by breaking and entering in their house. So Lalu put a different color light on the entry door to distinguish his house.
Next night Lalu came back earlier fully drunk. He saw the colored light found his house. He mumbled to himself, "This is my house, see the purple light."
He puts key in the door and mumbled again, "This is my house, see how the key fits in. He opens the door, enters and walks stealthily towards bedroom so as not to wake up the wife."
He carefully opens the bedroom door and with great victory smile mumbles again, "Damn it, I knew this was my house because there is my wife, and there I am in bed screwing her."