I am a horrible improviser. Really, really terrible and it's tomorrow. Any ideas how to at least be ok? How to survive? Tips...
The key with improv is don't worry about being funny. Take your required elements and do the very first thing that comes to mind. Don't over think it. Improv works best when you are impulsive.
Or if that sounds too scary :)
You can pre-plan how you will handle it. Maybe you will do it in the style of a commercial or a documentary. Or maybe you are an Alfred Hitchcock or Rod Serling (Twilight Zone) type narrator settin up the scene. If you narrate the scene and set it up before you perform in then it should give you time before you act it out.
For example, you are the narrator and you say, here is (character), he is in (setting) and this is when he (situation). Then you can throw in a twist or something else interesting... But you will be surprised by... Some other interesting thing you think up.
More improv tips and games at http://www.freedrama.net/improv.html