Who Says It's Bedtime?

As I sit here listening to Chippy scream, I'm not sure if I'm fond of his latest accomplishment. He now stands up in his crib. This is great during the day because he amuses himself by standing up - sitting down - standing up - sitting down. However, now that it's bedtime, Spot just doesn't measure up anymore. Now he throws Spot aside and lifts himself up on the side of the crib. He stands there screaming, not falling asleep. We've just called in reinforcements - Sprout is singing him to sleep ... fingers crossed ...