Oh my - this is a fun story.
It was the mid-90s - our last trip with then-15YO DS - and we were at Epcot, near where FW & WS connect. There was a big asian family (12-15 people) gathering for a picture. They obviously had one of those "timer" cameras, as one person put the camera on a cement post then ran to join the group. We were just walking by as this happened, so I stepped behind them - at 6'4" I was taller than any of them - got in the photo, then kept walking. What we all found the funniest of all was that no one noticed, since they were all watching the camera - and since this was before digital cameras, they wouldn't discover me in their shot. For the record, the did the same shot 3 or 4 times afterwards, so I know I didn't ruin a "once-in-a-lifetime" photo. But I still wonder if I'm part of some family's travel records....