Leave responses to the challenge as new entries. At the end of the week I'll compile all entries into a single post so that you guys can vote on the three you liked best.
Remember, you can submit captions either as simple text (be sure to specify speakers and actions/thoughts, etc...), or you can take the plunge and submit a modified version of the image with your caption included!
Have fun, and if you enjoy this community feel free to pimp it out a little. *grin* The more the merrier!