I need to get rid of the three monkeys that are on my back
Necesito quitarme de los tres monos que estan en mi espalda. Is this correct?
What about "Bueno, pienso que tomar manaña libre para que encargarme de los tres monos que estan en mi espalda"
Jeezzle, is this them?
I'm not sure that you will be widely understood if you try to use the expression. See this link. I read somewhere that it originated in English sometime in the 50's so maybe it's filtered into Spanish enough by now that it would be understood. I'm just not sure.
If I were going to say it, I would say:
los monos colgados de la espalda
los monos en la espalda
I see that some web hits like to translate it "mi espalda" but I don't think that Spanish speakers would use a possessive pronoun with a body part.
I did see several hits for "tengo el mono de..." with no mention of espalda and I'm curious if that has the same meaning.
Is that a common saying?
The best way to translate it exactly is: Necesito quitarme los tres monos (or 'changos') que están en mi espalda." (get rid of "de" after "quitarme").
As to your second sentence:
"Bueno, pienso en tomar el dia libre mañana para encargarme de los tres monos que están en mi espalda."
I know pensar en means to think about but doesn't pensar que mean to intend to? Gekkosan said mañana libre was OK in the earlier thread.