Would you eat a tuna, pickle, bean and turnip-green sandwich? With mayo and mustard? No? Well, neither will a certain litterbug, who tosses it into the weeds. Then it's up to other bugs-- Big Rig Bugs-- to clean it up.    Take the lead, millipede.   Clear that thicket, dozer cricket.   Pack it firm, pickleworm.   Chug chug chug, tumblebug.   (And I'll even give away the ending...)   See you later, excavator.