The restaurant Gabrincho, where I often ate pizza, closed down at the end of June. I went there for a final pizza last week, and was given a bottle of something very sour. It says on the bottle that it is seven times more sour than normal vinegar, so the intended use is that you add water to dilute it 7 times and then use it like vinegar. In the restaurant, they had used it for some kind of losing a bet punishment, where someone had to drink a glass of this stuff. That seemed unpleasant.
I carried this around with me the rest of the night (since I did not pass by my home) and at one place some people tried dipping their fingers in this stuff and then touching their faces just below the nose. That was also very unpleasant, it seemed.