It's a bright sunny day, and you're walking through the park with your dog. Your dog is playing and yipping and doing dog stuff, while you enjoy the scenery. A fit young woman is jogging towards you from further down the path. She looks at you and you nervously glance away, but she doesn't. She smiles and waves. Encouraged, you do likewise. Then you hear a giggle from behind you. Another young woman jogs up and greets the one you had seen wave. Of course she wasn't waving at you.