I actually like to play this game in reverse.
When I used to go out running with a friend, when we passed within earshot of people occasionally I'd make like we'd been running for ages, saying things like, "only 15 miles to go!" If not for little games to invent, running is far too boring.
The best one was when I was in Florence and my friends and I were making a mock documentary about the architecture there. We had all the camera equipment including a boom mic so it probably looked quite authentic. When it was a friend's turn to present, we were standing on a bridge and he was talking nonsense about it, such as that it was made of spaghetti and inspired a culinary revolution, and yada yada, and this woman who was walking by suddenly tuned into what he was saying, and spun her head round in surprise doing a double-take. I still have the footage showing her expression of bewilderment.
Moments like that are mildly satisfying given the lengths people go to ignore other people these days.