On this current tour BoRhap is the song that Green Day plays before 'Blitzkreig Bop'. As far as I know (since 'American Idiot'), Green Day plays 'Blitzkreig Bop' as background music and they have a drunk bunny come on stage to rile the crowd before the band hits the stage.
When I went to see Green Day in Virginia back in April, BoRhap was played and it got a lot of people singing along... not as much as they did in London though.