Running with a group is not for showing off. If some runners in the group want to pick up the pace, please make sure the other runners are not an afterthought. Save the race pace for the proper place. Be prepared for the call of nature. On familiar routes, make sure to scope out places ahead of time where you can do whatever you need to do with a minimum of fuss, be it at a gas station or behind a well-concealed clump of bushes.
Calls of nature happen.
Please don't litter. The roads are not your personal trashcan. Hold on to any litter until you find the proper receptacle. And, if you want to get a gold star on your road-manners report card, plan a run where you clean the litter along the route. Smile at other runners as you wend your way along your route.