Do you know how lie detectors work? They measure your heart rate, breathing, and other indicators from your nervous system to determine whether or not you are telling the truth in response to a series of questions you are asked.
Evidently our bodies are biased toward truth and honesty and when we violate our own integrity, our bodies respond in kind. When we lie, our bodies telegraph "that is not the truth."
Do you know why this is so? It is because we are created in the image of the One who is integrity, truth, and fidelity.
Do not violate your nature. Tell the truth even if it gets you in trouble.