I have a few times. I always let my figure handle it. One time a fellow who obviously had a little too much celebration kept interrupting us. I had Larry turn to him and say, "Please sir, I only have 10 minutes to make a fool of myself and you have all evening, so, could you please stop interrupting me?" The audience LOVED it, and he was one of the ones who laughed the loudest. One time I was performing in an old theater. Larry told a REALLY bad joke (deliberately, of course) and someone in the audience hissed! Larry asked what that was, and I asked what was what? He said he heard a hissing sound. I said it was probably one of the old air hoses or steam pipes back stage. Larry said, "I think it was both!" I asked, "How do you figure?" He said, "It sounded like hot air escaping!" Again, the audience ate it up. It's always good to have a few bits of business ready for times like that. It's called "Prepared improvisation." Old timers used to call it, "Calculated Theatrics." If you're prepared for situations like that you won't get side-tracked and forget lines and such. It also makes you look like a quick wit to the audience. I've heard audience members say to one another, "Boy, he's quick!" Like the Boy Scouts motto, "Always be prepared."