Steve-O's new opening act on his comedy tour is Bam Margera ... and the 'Jackass' alums hit the stage together to workshop some new material.
We got video of Steve-O shocking the packed house at the Elsinore Theatre in Salem, Oregon last Sunday -- and Bam's surprise appearance drew huge applause from the crowd.
In the video, Steve-O helps Bam work on some jokes ... comparing Bam's life to Britney Spears' and telling a few stories from rehab.