I have to echo what anvil said earlier. When I was drinking, I almost always tried to lie about it, and maybe a few follow-up lies to cover my tracks to account for the before and after. Otherwise, I very rarely lie and I pride myself on that. It's the insanity that drives us to do anything - including compromise our morals - to protect the continuation of our habit. I remember being confronted by my ex about it when I had only had a few shots, and the first thing I felt was terror that if I admitted it, he would then demand to know where the bottle was so he could dump it, as he had done in the past. I used every faculty of my brain to protect that wicked bottle from being emptied. Sigh.
But I have to note that often people characterize alcoholics as by definition pathological liars, which is not always the case. I've known pathological liars, and they'll lie about anything and everything for no discernible reason from literally what they ate for breakfast to what their great aunt does for a living. I knew I was lying, because if someone believed me (or pretended to), I felt a giant sigh of relief.
It's part of the insanity of it. Most alcoholics I know are exhausted having to remember various lies they told and feel tremendous shame about the consequences of these lies.