Why does she ask why all the time ??????????

So its been a long time since I posted anything well to me its been a long time. Today I had to write about this. My daughter who is a sweetheart has turned into a why-bug. Really I mean it and I thought it is a phase and will go away soon but nope the why-bug has bit her and she keeps asking me why for everything and it gets to you after a certain amount of WHYs. if she wants something that she is not supposed to have she will ask why and when I answer her with the reasoning then she asks me why ?? when I say don't keep asking why she asks me why. I am really getting tired and trying to find an answer for this. Do any of you know the remedy for a why-bug bite >>?? if you have the answer to this one I'd really appreciate the solution. I know, I know that all the parenting magazines and books I read tell me that you should never stop your kids from asking questions but tell me does it not get to you ??? I am still trying to find the best way to treat this....maybe tomorrow she will wake up with a smile and say no why's today mom :) oh that will be music to my ears.