google street view
Reddit User: cpt_hammer
Google periodically updates and expands their Street View service by sending camera-equipped cars out into the countryside in order to map out roads.

A Reddit forum-goer spotted one of the cars in Cardiff, UK and took a photo. Then, she waited. After a month, Google Street View was updated with photos the car took that day. One of the photos included the Reddit user. You can tell because the guy on the bike is the same in each photo.