"Bounce off" is a phrasal verbs which means to brainstorm an idea. This is usually used when two people are trying to think of a good idea by free-thinking (saying words that first come to their mind when they are thinking of an idea). i.e. We have to have an idea by afternoon on how to increase sales. Let's bounce off of each other to figure that out.

Since your question didn't specify, here is an example using the traditional meaning of the verb "to bounce": The ball bounced off the table and hit me in the face. There is also the phrase "bouncing off the walls" which describes someone who is very energetic or stir-crazy and can't stay still. Example: These kids are bouncing off the walls! How much candy did you give them? For the phrasal verb Nick described above, I've typically seen it with an object: "to bounce something off someone". Usually an idea or a plan of some kind.