Awkward, Awkward

I guess, one thing everyone wanna escape are those awkward and embarrassing moments. Such as an unreturned high five. Or saying good evening instead of good morning accidentally. Or when a friend leaves you with a friend of his. Or shouting in a public place unintentionally grabbing all the attention. Or burping loudly in a quiet place. Or accidentally mistooking a pedestrian as someone else. Or tripping infront of notables. Or leaving a shop without buying anything. These are the worst types of circumstances. But why do these unpleasant memories remain while the happier ones do not?