The lies that are hurting you in these ways are not the ones about the mystery drink your parent is consuming. They are also not the lies you'd find out about anyway.

Your kids aren't determining their trust in you on the veracity of every minor interaction you have with them, and if you think that's a dubious statement, you are underestimating the vast, VAST number of interactions you are gonna have with a kid just in one day.

By all means, be honest with your kids, but drink your own milkshake and also screw with your kids so they don't end up weird.