This happens to me occasionally. Generally, the next step is for me to call attention to how flat the joke fell and then go on my way.

Sometimes, though, I come up with real winners. The other day I told my friend I had used all the toilet paper in her bathroom to clean up some paint. I tell her she shouldn't use that bathroom.

What does she do? What do you think?

Friend: "...hey! There's no toilet paper in here!"
Me: "I told you this five minutes ago. I said not to use this bathroom."
Friend: "Crap!"
Me: "I hope not."