I've been so absorbed with thoughts on reductio proofs today that I forgot that it's Friday! But in the spirit of dialectic and adversarial encounters prompted by the conference on dialectic and Aristotle's logic that we hosted this week in Groningen, I was reminded of a peculiar Brazilian folk tradition, that of the Repentistas. These are duels involving two musicians, where each improvises the lyrics as they go along, attempting to ridicule their opponent -- in other words, very much in the spirit of ancient dialectic! (Historically, the tradition traces back to the medieval troubadour tradition.) The name 'repente' means 'sudden', and refers to the improvised nature of the music.
There are two kinds of repentes: accompanied by guitars, called 'cantoria', and accompanied by tambourines, called 'embolada'. Below a video of two emboladores performing in the center of Sao Paulo, and here a link to an album entirely dedicated to repentistas. Things can get quite aggressive with these guys!