Modular cocktails.

[Crumplehat]

The thing is that only you, the bartender, would know the name of the cocktail, unless a scientist is sitting there scanning them or something. Only the barman can identify the ingredients of a drinking glass otherwise, and only while drinking it. Which is a double-edged sword because on the one hand, people can't tell if you're slipping poison into their drinks, but on the other hand they can't tell if you've given them some awesome rad drink either.