How can I flush the trace of drugs out of my system before a drug test?

I made the small mistake of smoking marijuana with a few friends last weekend. I normally don’t do this, but I figured it wouldn’t be a very big deal since it was just a few puffs. Now I am being forced to take a drug test when I get back home from spring break. I was not aware that I would be subject to drug testing when I took my job as an opera singer. Is there anything I can do to flush the trace of drugs out of my system? Are there any tricks that I can use to pass? Drugs don’t leave my system very quickly and I know it will be present in the results. (It will either be a urine or saliva drug test.)