Here's the heads up thread, post in it if you want to let others know that you're joining.

So yeah, the collab will take place this sunday (23rd May) at 5pm (UK time) 12pm noon (Eastern Daylight time - The time Newgrounds runs on) in the Collaboration forum. I will post a topic at that time which will include the theme of the collab, specifications and some useful information. I will also answer people's questions and tell people how much time is remaining and stuff. Hope to see you there!