if you lie and say you didn't smoke then come back positive the judge may just be pissed enough to put you in comtempt(yes they can do that,in that courtroom they are god and they know it)so dont cry inocent unless you are 1465793460760647664565656546% sure you will pass and not to sound harsh but you put yourself in this situation,as much as i hate to say it.but i dout they will send you to a juvinile detention center,but ask who the judge hearing your case is and try to get some background information on his/her ruleings,and your going to HAVE TO quit smokeing,cold turkey,no more till your off,if you fail again the will 100% send you to a juvinile detention center for three months or more if they can manage it.but good luck,hopefully you'll just get a few months more probation,hope for the best but expect the worst i followed your first thread when this all started and i know you've had some rough times,so good luck