A Radio (or something that resembles one). Originally done by SNL
The scene is a living room with a radio playing. A scout is changing the stations. There is an announcement, read from offstage. “We interrupt this station to bring you an important announcement. A criminal known as the Land Shark has just escaped from prison and has been sighted in our town. He knocks on the doors of unsuspecting people, disguises his voice, and when they open the door he devours them up and leaves no trace. If the Land Shark shows up at your door, do not open it! Call the police immediately. We now return to our regularly scheduled program.”
Scout, turning off radio, says, “I hope that Land Shark doesn’t show up here!” Immediately three loud knocks are heard. “Who is it?” Offstage voice: “Pizza Delivery!” Scout: “Oh great! Come on in.” He reaches offstage to open the door. Hands reach out and pull him offstage with a large growl.
Scene changes as another Scout assumes the position in front of the radio. Scout: I’ve heard so many rumors about that Land Shark, I’m curious. (Three loud knocks) Who is it? Offstage voice: Luke Patterson from Metropolitan Life. Scout: What do you want? Offstage voice:I need to review your policy. You never know when something might happen. Scout: Come in! (Opens the door. Loud growl. Scout is grabbed and pulled offstage.
Scene changes as an older scouts takes the position in front of the radio. Scout: (Three large knocks.) Who is it? Offstage voice: Pharmacy delivery. Scout: I didn’t order any medicine. Offstage voice: Singing telegram! Scout: From whom? Offstage voice: (A little frustrated) It’s the plumber! Scout:My pipes are fine. Say, I know who this is, it’s the Land Shark! I’m calling the cops. Offstage voice: (reassuring and friendly) Actually, I’m only a guppy sir. Scout: Oh, well I guess you couldn’t hurt anything. (Opens door, loud growl. Scout is dragged off stage.
Scene changes as a sharp looking Scout takes the position in front of the radio. Scout:(Three loud knocks) Who is it? Offstage voice: Boy Scout Troop 144. Would you like to buy some fertilizer, sir? Scout: (Looks warily at audience and smiles knowingly. He picks up a large stick and prepares to hit the Land Shark.) Come in! He swings the stick offstage. There is a loud thump. A very young Scout in full uniform stumbles onto the stage and dramatically falls face first.
Here’s an example-