The TSA-Bash is an annual get-together for those interested in physical transformations (or furry in general) for the expressed purpose of "goofing off".
Unlike furry cons, the "Bash" (as it's known for short) doesn't have a "conference" type quality to it. Instead, the attendees just sit around and chat, play games, go out to eat, and sometimes model fursuits. While there is a chaotic quality, the Bash does have a couple of structured events, such as a group photo or outings to the city that they're close to.
Discussions and planning for the TSA-Bash takes place via the TSA-Bash mailing list - if you're interested, join the list! For information about past and upcoming Bashes, there is also a Bash website showcasing pictures, stories, and detailed info pages, maintained by Sheep.