'Roach Coach' is the slang term for these catering trucks that move from place to place selling coffee, donuts, sandwiches, etc. They usually stop at places that are too small to have their own cafeterias for the workers. These include construction sites, etc. The term comes from the fact that they are motorized and may be ferrying cockroaches from place to place with their food (BLEAH!).

In your context, they are playing off the slang term and just using the cockroach part.