You pour ice and water down yourself... But, what cause is that supposed to help? It is supposed to magically give homeless people food? No, i don't think so. This "cause" is only making people scream like little girls.
It's helping a lot though, what was that other one that was done recently? I think it was selfie related... That raised multiple millions, the idea is that you get nominated to donate some actual money, and then you do the ice bucket thing to bring attention to that fact, to prove that you can act on it.