It can't be placebo since you know it's placebo

Placebo only works if you believe it's not placebo ;D
If you are sick and I give you pills and say that "These pills are just normal and harmless and contain only normal salt, but you will get better because of placebo effect." you won't have any placebo effect.
BUT if I give you the same pills and say that "This is the new groundbreaking medicine for this decease and should make you feel better in a few hours" then you might have placebo effect if you actually believed what I said and trusted in me...
EDIT: ninja'd by IRNjuggle28