Joke stolen from: Chucklebuns

I put a roast in the oven one noon hour and set the timer, a feature I hadn't used yet. Before leaving work that afternoon, I phoned my 14-year-old son to ask him to check the roast and peel some potatoes. Minutes later he called back. "Mom, the roast isn't cooked. The oven didn't come on." The roast was on the menu again the following day, but this time, since I stopped by the house after a business lunch, I decided to turn the oven on myself. Again before leaving work, I called my son to check the roast and get the potatoes started. Again he called me back. "The roast still isn't cooked." "Listen," I said. "I know the oven's on. I turned it on before I left. I didn't use the timer." "Oh, the stove's working fine," he told me. "It's just that the roast is in the fridge."