First let me start by saying that there is nothing that will get thc out of your body. Thc is store in your fat cells and there is no chemical/drink and trick to get it out faster.
Go to your local vitamin shop/gmc or health store and look for a herbal clensor. My personal choice is called q-carbo, I personally have used it to pass at home drug test the morning after a night of smoking. My friend has even used it to pass state drug test for diversion programs. Bassically all q-carbo is, is an overdose of vitamins and nutrients in a bottle with a mix of niacin and other chemicals to make you **** like a race horse. The over dose of vitamins and nutrients bassically dilutes the thc in your body and allows you to drink an incredible amount of water while still makign your **** look yelllow. Trust me if you arent drinking **** tons of water this **** will make you **** green. My best advise is to start drinking water now, dilute your **** as much as possible. Other than that, go to your local head shop and pick up some fake *****. Some will come with apparatus's to strap them to your inner thigh some will just be a liquid. If you get just the bottle of liquid with fake **** I reccomend pooring it into a condom and going to your local store and picking up hand warmer or glove warmers to keep that **** warm. You dont want to hand them a cup of cold "****" they will know.