Very seriously restricting blood flow to the brain may produce one of the most powerful arousal effects. Brain deprived of blood may create this hallucinogenic effect. The deadly dangers involve very high chances of passing out instantly at any moment and then getting strangled/hanged to death. But even if doing it with a partner who will cut you loose, still there are additional dangers of heart attacks after the oxygen and blood flow starts to rush back after the noose is removed. And always the possibility of broken neck damage while in the process of hanging. In other words, stay away from it.