My favorite preshow announcement has to be the Ka - Cirque version. For those of you who don't know, when you walk in, the stage is basically a big pit, with occasional bursts of flame coming out of it. A couple of cast members came out, walking on the ledge along the front of the stage, and they 'spotted' an audience member with a camera around his neck. So they pulled they guy out of his seat and grunted at him. Took the camera and threw it into the pit. And then there was a large burst of flame. They searched him, found a cell phone and just set it on the ledge. And then they addressed one more thing... I don't remember what it was, but they threw it over the ledge, too... They were sending the guy to sit down, and he grabbed his phone off the ledge. And a second later, it rang. So he was pulled out of his seat, and they threw HIM over. Large burst of flame.
I've done announcements before where I'll have a plant in the audience, and their phone will ring just as I'm announcing that phones should be off... So I take it from them, answer it, and tell the 'caller' that so and so is in a show right now and would return the call when the show was over.