Never Leave a Baby Unattended, Here's Why!

OK. This is really funny. True story, BTW. OK, so once upon a time, a relative of mine, was a cute, innocent baby. Her parents had a celebration. And during the celebration, they left her unattended, and she did something hilarious and genuinely wrong. Fast forwards a bit and She's running around like a madman and rolling on the floor randomly. Everybody wondered what had happened, and because she couldn't speak, she decided to demonstrate (Read: She randomly did it again, in front of everybody). She took a cup with alcohol and took a few sips. So that's what had happened. Can you try to guess the lesson of the story? (Hint: Read the Title!)