Ingredients:
1/2 Glass Guinness&Reg; Stout
1/2 Glass Root Beer

Method:
CAREFULLY to avoid explosive head formation: Pour Beer glass half full of favorite rootbeer and top off with Guinness.

I prefer Henrys for the rootbeer (cold) and the Guinness warm and flat. I have used other beers and for me stouter is better. Porter works. You may vary the 50/50 proportions to taste. One of the most charming traits of this drink is the disgusted looks you get when you order it.
Serve in: Beer Mug