Quote Originally Posted by rsad

What happens if the lab catches a sub?
If you are at the collection site, and the collector catches you with any "cheating contraband", then you will be submitting a urine sample under direct observation. If you refuse to submit under direct observation, it will be declared as a "refusal to test".

But as long as you play your cards right and not do something ludicrous like keeping your sub container in your shirt pocket, etc; then you have nothing to worry about.