ive never heard this
why
I mean, there's really no exact science behind it as far as I know. It's just recommended because alcohol thins out your blood, so it could interfere with the initial healing process. The first 72 hours after getting a tattoo are the most important because that's when the surface of the skin heals the most, so you've gotta wash it and lube that stuff up really often to prevent infection. Adding alcohol into the mix kinda messes with it.