The BBFC wasn't very amused by the drug consumption, but at least the scenes with the soft drug Cannabis have not been cut. But it was more bothered by the "strangling until unconciousness", which is thoroughly shown in the movie, on Steve-O as well as on stage on some fans.
Due to the possibly dangerous consequences for copycats, all scenes of that kind had to be removed. Scenes in between, showing people talk about this have been left in for no reason. Some other cuts, e.g. the ones with the naked women in the beginning are rather questionable, too...