No drinks really work, even if they clean out your pee (Doubtful since THC is stored in oil, and any water based drink is doubtful to have any effect at all), the color of it will throw a flag and make your test "inconclusive", so you will need to go back to be retested, or they won't even bother to call you back. Honestly if you smoke, synthetic urine is the only way to go. If it's for a government position you may need order the Quick-Fix from Canada which has Uric Acid, though it is very rare to have a drug test that also check for Uric Acid.