Well, whens the last time you smoked? As far as I know it takes 5-10 days for the THC in your blood nourishes the hair follicle and is then detectable. Also, your hair grows roughly 1/2 and inch every month. However, your body hair grows way slower. In my case I smoked once at the end of July and not since then (sucks right, but I don't have a source right now so I didn't have a choice). Anyway, I just figured out how much hair I had to keep on my head based on the calculations above (turned out to be an inch for me, just to be safe) and then I shaved my body hair. Just tell them, your girlfriend doesn't like it, or you lost a bet, your metro-sexual, or don't tell them shit, as long as you have enough hair on your head they don't even look (when I had an inch on my head they didn't even look at my body hair). However, if you smoked too recently to leave any hair on your head, you could probably shave everything, but you would be suspect for sure. Still I think they could only make you take a urine test or I think they might take fingernail samples (I have no clue how that works). As far as the shampoos and shit go, I think they're all bullshit, just b/c the THC is in your hair, not on the outside, after they take the hair sample, they wash the shit out of it anyway. In fairness, I haven't tried any shampoos, but I doubt they work. Hope this helps, how fucking ridiculous that you have to go through all this shit. Just remember to consider the 5-10 days it takes for the THC to get into your hair when you are calculating hair length. Good Luck.