"Dear next door neighbor, the next time you bring a girl home, please try to be quieter." You have been writing to the red-haired man next door for about fifteen minutes.You didn't know how much he would care or if he would bother to read the letter, but there was no harm in trying. When you finished writing and got up to put the letter on his doorstep, you saw him entering his own house. When you handed him the white paper, he looked at you with curious eyes.

What is this?