Velvet Revolver / ex-Guns N’ Roses bassist Duff McKagan got down with Down in concert, sitting in with the band Monday for the song 'Bury Me in Smoke' at a show in Sao Paulo, Brazil. Duff McKagan's Loaded were also on the bill, making the all-star onstage collaboration an easy one to pull off.

Down -- the heavy metal supergroup featuring former Pantera singer Phil Anselmo, ex-Corrosion of Conformity guitarist Pepper Keenan, Eyehategod drummer Jimmy Bower, Crowbar guitarist Kirk Windstein and bassist Pat Bruders (who took over fro Rex Brown earlier this year) -- are currently on a South American trek that is scheduled through a gig on Saturday in Mexico City.

Also during that gig, Anselmo got a little carried away and ended up smashing the microphone into his forehead repeatedly until a little blood seems to appear.  How metal is that!?

Video of both McKagan collaborating with Down and Anselmo attacking his forehead can be seen below:

Watch Duff McKagan Rock Out With Down
Watch Phil Anselmo Bash His Head With a Microphone