Explain the nurse's two stories about juliet as a toddler.

The Nurse tells the stories when Lady Capulet come to tell Juliet that Paris wants to marry her. The first story is about the day that Juliet stopped nursing. The nurse used a bitter wormwood on her breast to make nursing less appealing so Juliet wouldn't be interested. She wasn't happy and when she started to fuss about it there was an earthquake. 
The second story is about a day when Juliet fell and cut her forehead. The nurse's husband told a joke saying that Juliet would learn to fall backward instead of forward. When he says fall backward, he is referring to her falling onto her back in order to have sex. The nurse says that his joke has come true since she's about to be engaged.