What's the Point of a Smoking Gun?

I think they are keeping things relatively tight, uh, to a certain extent, about how the length of these. But i do think that, you know, this does seem like it's going to be a multi media presentation is sort of knock people over over the head. What would count as a smoking gun? One would be the president's own word, rds, whether repeated by somebody who stood right next to him or in some other fashion,. I'm saying that if it does, that would be a pretty big deal politically.