Disambiguation: Is the cake a lie? No! Cake may refer to...
Common planning for Mapping Parties is to create a 'Cake diagram'. That is to take a map image of the area to be mapped and draw lines on it to form 'slices'. Each mapper can choose a slice that they will map. It can be scribbled lines drawn over a map image, or tools like MapCraft offer an online interactive cake diagram experience.
This is a test of the openness of the license. For OpenStreetMap data, and map images created from that data, based on the current license: You can print or ice a copy of(or image based on) the map but the attribution text "OpenStreetMap.org and Contributors, CC-BY-SA" should be included (by be preceded by something like "Map Data: ". If you can't ice that on the cake, then the attribution on inedible paper next to the cake should be sufficient. How you represent the map (e.g. what colour icing) is free to be copied by anyone under the same terms (i.e. attribution must be given, any changes remain under the same terms again).
Please note that the OpenStreetMap logo is a trademark registered by the foundation and you should get permission to use that. If you offer a slice of cake to any/all foundation members present then you will probably be okay.
Blog posts about the cake test...
A lot of mappers make cake that you can eat. Sometimes it satisfies the cake test above, sometimes it has no map and is just for a celebration. OSM Birthday time usually generates a few cakes around the world. It can get quite competitive! (but Japan is winning)
Blog posts about edible cake, and examples
- 5th OSM Anniversary in London - and Cake Competition
- London Parties - includes jokes about cake test attribution
- Toronto Cake
- Cake Map Tiles
The term "Cake" became associated with OSM as a result of the early mapping parties, specifically Mapchester, the first mapping party in Manchester in May 2006. A "Cake diagram" was produced to help with the mapping effort (top image)