These used to be popular for apprentices who had completed their apprenticeships ... Invariably male, the young lads were stripped naked and had their testicles painted blue and red if they were trainee decorators. Motor mechanics would have their genitals rubbed with engine oil whilst plumbers would have nuts placed on their nuts. The rites were inflicted by the older men in the company and were performed in front of crowds of cheering fellow workers. I think these initiations stopped in the 1980s when female apprentices became a possibility... Some ceremonies went too far needing medical treatment ! The Americans called it "hazing" and it involved college boys ..