i don't perform yet ... but my routine includes slush powder this very scrupulous device is really enhanced with a little milk jug type thingy. i first
"pretend" to pour out water with the little tingy then hold it up and accidently spill it on the audience... ofcoarse nothing comes out... then after i get more water and PROVING the water is still in there i then mix up the empty cups rapily and occasionlay spill them... the with the loaded cup i move EXTREEMlLY slow. thus creating an effect where it is IMPPOSSIBLE for the audience to get it wrong.