My bad!
I think it's good - it's healthy - for people to admit their mistakes. In fact, I believe that a person actually experiences healing when they fully admit either to themselves, to God, and/or to another that they were in the wrong. Let me explain.
I have a friend who jokingly says, "My bad!" He says it quite often, and then laughs like crazy. For the longest time I had no idea what he meant by that statement until I saw it on television during various team sports events - when a player would make a mistake of some kind, they would often turn to their teammates or to the bench and motion toward themselves in some way -- I learned later that they were saying, "My bad," in other words, "My mistake!". And I suppose I'm suggesting here that 'admitting one's mistakes' has, in many ways, become fashionable, perhaps not very genuine, in my opinion.
Jesus tells a story in the Gospel of Luke about truly admitting our mistakes and our shortcomings before God and before each other. He notes in the story that when we honestly see ourselves as less than what God wants us to be, we receive healing, and God is pleased with our honesty. We're not suggesting here that God wants us to be a "doormat". What we are saying is that God wants us to find the source of our honesty, our clean heart, and our goodness in Him.
Perhaps, then, "My bad!" is a very good thing. After all - you and I treasure an honest person, especially when they admit that they are wrong!
When we admit our mistakes, God is pleased with our honesty.