What are ghost truckers what do they carry?

i watched a show they said that theres a line of trucks called ghost trucks and they carry top secret things. does that mean they are the people who transport nukes and donets for failed attempts to mind control and other top secret plans ( the us is still trying new things and tried things since the 50s) ( watch the discovery and history channel ) cause i know less powerfull bombs are carried by non ghost trucks. does anybody know what they carry. anybody used to be a ghost trucker.