He wads up his gum, throws it over his shoulder, and walks offstage. Second person walks in. Halfway across stage, they stop. They've stepped in gum, it's all over their shoe. They make a face, pick the gum off their shoe, wad it up, and throw it over their shoulder.
Third person is a jogger.
The gum lands in their hair. They pull the gooey gum out of their hair, it's really stuck in there, eventually they pull most of it out, wad it up, and throw it over their shoulder. Fourth guy is walking his dog and stretching. The gum lands in his armpit. He pulls the gooey gum out from his armpit, wads it up, throws it on the ground.