You mean you get caught for smoking pot? Or eating hemp? lol
No, hemp won't show up on a drug test. There are no narcotics in hemp to affect the human body - it is a COUSIN to the marijuana plant, but they do not have the same properities.
There are lots of vegetarian athletes who eat hemp daily for protein (ie. http://www.myvega.com).
If it indeed showed up on drug tests, they wouldn't be allowed to complete.