Snot Ettiquette

I was sitting in my office this afternoon talking with David when he said something mildly funny. The shock of this made me snort slightly and a huge lump of stuff flew out of my nose and landed on my shirt. I think I may have a bit of a cold coming on. I just continued as if nothing had happened, and hoped that David would not mention it. Which he didn't, being a polite sort.

Now, the question is, what is the correct procedure when this happens? (and I'm sure that it has happened to you all).