Yoko Ono and the Plastic Ono Band made a music video of her song "Bad Dancer" in which Ono and other celebrities dance badly and joyfully. (http://www.youtube.com/watch?v=d3mvEfON2CI) The idea of the song is that we should free ourselves of the burden of "being good" and embrace being bad at things, so as to do them freely.
This idea can be applied to any activity in which fear of poor performance prevents us from acting with freedom. For example, "Bad Presenter," "Bad Singer," "Bad Listener," "Bad Writer," "Bad Artist," "Bad Translator," "Bad Innovator," "Bad Activist," etc.
Participants prepare a three minute presentation that they will give in front of the group. The task is to prepare a "bad presentation" -- a presentation that is ineffective, weak, hard to understand, etc. The presentation can be bad in terms of content and/or presentation technique. The audience will judge each presentation, giving a prize to the worst presenter.
At the end, identify the keys to a bad presentation. (No need to take the next step of identifying the keys to a good presentation.)
"Bad Answer" -- same as above but a panel competes to give the worst possible answer to questions from the audience.