I grew up here in RSA with all this shit.It's all bogus!!!
Ask them to make you win the lottery or the jackpot at the casino.Alot of the black nations in Africa has these types of beliefs and we have Zulu,SeSotho,Northern Sotho,Pedi,Xosa,Venda,Tswana and Bushmen(San) in South-Africa alone.All these nations with different beliefs.
The bushmen have a "poison mixture" wich they have to drink to kill themselves if they have done something dreadfull in the eyes of the tribe or group or family.They then go to sleep and the next morning they are dead in their bed.Not painfull or anything,you die in your sleep and that is your punishment.The interesting part is that this "poison" was analized and tested by Docters and professors at the University of Potchefstroom in South-Africa and they found that it was totally harmLESS!!!!!!If you understand the black people way of thinking and living here in Africa you'll understand their minds is a lot stronger than their hearts or bodies.
If a witchdocter casts a spell for e.g a man to die in the bush by the lion, he will go into bush to look for the bloody thing!!!!!Their minds make them sick and their minds heal them as well.