There is a term in Portuguese "choro" or "chorinho", that can be used in a context like this:
O barman me serviu uma dose the whiskey e deu um chorinho
meaning
The barman served me a dose of whiskey (I have paid for) plus a little bit more for free.
In Brazil people expect barmen to serve a little bit more that the dose they paid. Barmen (bartender) that don't do that are not well seen.
Is there a word that can be used in that context, or a construction that means the above, without using the ugly construction I have used to explain?