If you forgot to thaw the ground beef the night before, you can thaw it quickly under running water.
Place your ground beef, still in its sealed container, (plastic wrap is ideal because it's airtight but still allows the water to get close as possible to the beef, as opposed to say, a Tupperware container) in your sink. Turn on the faucet and let it run lukewarm (cold will be too slow, hot will cook the meat) water over the beef. Both the temperature of the water and the pressure from the faucet will give you perfectly thawed meat as quick as possible.