2nd-hand pot

Well you just have to give it time to grow out without any drug traces.

I've heard in cases they can trace it to 7 years. But who knows.

Anyways, just drink plenty of OJ and work out. I've got friends who have went from smoking nonstop to getting clean for a test in a week and a half. He drank like fifty bottles of water or something and did nothing but run on his treadmill afterschool all day. I know you didn't smoke or anything but i'm not gonna lie when I hang out with my brother and his friends in their room, i get somewhat high from not even smoking. Besides, you'll feel better after eating healthy/drinking water only so its a win-win situation.

Edit: From wiki,(turns out i was very wrong but its wiki so who knows how accurate it can be)
Hair drug testing

Hair testing is considered highly accurate and can go back normally 3 months (6 months or longer possible with specialist tests), showing any drugs of abuse used in the detection window. As hair grows out, any drugs used are encased in the hair shaft, so the longer the hair, the longer back in the individual's drug history the laboratory can detect. Accredited hair drug testing laboratories, however, only use hair within about 2.5–4 cm of the scalp, and discard the rest. With head hair each 0.5 inch (1.27 cm) corresponds to about 30 days. This limits the detection history to about 90 days, depending upon the rate at which the individual's hair grows. Some people attempt to circumvent this through shaving their heads. In the absence of the required amount of hair on the scalp, body hair can be used as an acceptable substitute.

Additionally, for pre-employment hair testing, the inability to obtain a sample may be grounds for not hiring the individual. Hair Testing labs are regulated by CLIA or SAMHSA (not FDA). There is a growing trend in major companies and law enforcement agencies to utilize hair analysis on account of its efficiency and reputation as the gold standard when considering test accuracy. This technology makes use of radioimmunoassay technology with subsequent confirmation by mass spectrometry.

In recent years, hair testing has been the subject of a number of law suits. Studies have shown that different ethnic groups have different hair structure, potentially leading to false-positive

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so in a positive note for you grav, you can say "but.. I'm fat! My hair structure is different!"