MEPS: drug history question?

I go to MEPS in two weeks and I'm attempting to get into intel or cryptology (IS/CTI/CTR). These rates require TS Security Clearances. I smoked some pot in high school (I am now a college graduate and haven't smoked for over three years). Should I lie at MEPS and say that I've never smoked marijuana? I've seen this question before and most say it would be better to tell your recruiter or MEPS doctor about it bc they will find out anyways. My questions is this, has this ACTUALLY happened to anyone? Has anyone lied and then the FBI later found out about their drug use? Please advise.