It took exactly once when I was 17 and my mom knew. I only took around 2 shots worth and she immediately knew. My solution? I'd take very small amounts over the course of a week and hide them in a cup and then when the weekend came I had a few shots worth. I never replaced it, the amounts were just so small they were imperceptible to her eye.
And then other times, like prom, I'd just take it and deal with being yelled at.
And then other times, like prom, I'd just take it and deal with being yelled at.