Go to your local smoke shop and bring about $40 and get yourself and bottle of "Instant Clear". Clears your system, free of THC :thumbsup: (Sorry if anyone already recomended this)

I dont know if they can tell that you drank somthing to make you clean, but I know that it worked when my parents were all anal back in the day. Or there are these things called "Wissonators" or somthing like that... Sorry if none of this is helpful. Good luck man!