He had two prior appearances discussed here:
http://forum.galacticwatercooler.com/showthread.php?t=5093&highlight=robot+chicken
I found one more that wasn’t mentioned in this thread- he plays the cheating husband who’s sleeping with the chick voiced by Tila Tequila(!)
http://www.robotchicken.org/index.php?title=I_Am_Needed_Upstairs