When I was in college, I knew a young man who had a very interesting childhood, a young man who loved to tell stories about all the odd adventures and misadventures he'd had while growing up.
I remember, when I first knew him, sitting in the cafeteria eating supper and listening him telling the most fascinating stories. I remember thinking to myself, "How in the world does one person have so many strange things happen to them?" And I remember thinking, from time to time, either "Why couldn't my childhood have been this interesting?" or "I sure am glad my childhood wasn't like that!"
Then one day, when he was telling one of his childhood adventures, I found myself thinking about one of his previous stories he had told a month earlier, and thinking to myself, "How can both of these stories be true? They seem to contradict one another!"
From that point on, I began listening to his stories with a much more critical ear, remembering previous stories and comparing them to current stories, and looking for ways in which the stories didn't match up. It didn't take long before I realized: "None of these stories are true; they exist only in his imagination. And if any of them are true, it certainly isn't worth my time to try to figure out the difference!"
Gradually, everyone in his circle of friends began to understand that he was a perpetual, habitual liar. And soon everyone began distancing themselves from him. We all had better things to do with our time than listen to him tell stories that we knew weren't true.
Eventually, he got a whole new circle of friends, but that set of friendships was doomed as well.
I understand the desire to make yourself look good, and telling a few carefully placed lies can be one way to do that. But the cost this young man paid for "looking good" was far too high. When you give in to the temptation to speak falsehood, ultimately it becomes impossible to sort out your lies and keep them consistent. Ultimately, your sin will find you out.
1 Peter 2:1 tells us to put aside all deceit, and lists this as one of the prerequisites to having a sincere hunger for the Word of God, and of growing up spiritually. A person who indulges in deceit is a person who will never grow into a healthy, spiritually mature man or woman.