Great idea! Challenge accepted... oh wait there wasn't one. LOL Here's a Res-C Bussekin square for something creative.
Seriously though, basically the person who starts the challenge comes up with an idea/rules for the rest of us to try to achieve and capture in a photo. For the Busse Challenge Thread on BF, the challenge all involve/include Bussekin knives in the winning photo as a requirement. Then who ever posts a qualified photo created after the challenge is issued wins the round and goes on to issue the next challenge. In this case, since my photo is from many months ago, it would not be accepted for a challenge issued last night. It's a unique way to generate new pics/posts when things are slow and it's fun too. I may have forgotten some of the details.