Rufar means to rumble or to beat, specifically referring to drums. It's a less common verb that evokes a very specific sound and image.
In "Conexão Amazônica," the line "Os tambores da selva já começaram a rufar" (The jungle drums have already started to rumble) uses this word to create a vivid, almost primal atmosphere, signaling a shift or an impending event. It's a powerful and evocative word that stands out in the lyrics.
Legião Urbana open this one already worn out by talk. "Estou cansado de ouvir falar / Em Freud, Jung, Angels, Leonard" ("I'm tired of hearing about / Freud, Jung, Angels, Leonard") lists off big names as barroom noise, and the next line says so outright: "Intrigas intelectuais / Rodando em mesa de bar" ("Intellectual squabbles / Happening at a bar table"). It's a complaint about people who talk instead of act, not a philosophy lesson.
Then the song turns harder. "Os tambores da selva já começaram a rufar" ("The jungle drums have already started to beat") sounds ceremonial until the next line cuts it down to a supply problem: "A cocaína não vai chegar" ("The cocaine won't arrive"). "Conexão amazônica está interrompida" ("The Amazonian connection is interrupted") gives the song its title, and it's a trafficking route, not a spiritual one. By the last verse the warning is plain: going broke and pretending it's fine, "E você quer ficar maluco sem dinheiro e acha que está tudo bem" ("And you want to go crazy without money and think everything's fine"), just leaves you alone with it, "Auto exílio nada mais é do que ter seu coração na solidão" ("Self-exile is nothing more than having your heart in loneliness").