A new kid from overseas came to Beijing, named Dre, you and Dre became friends, Cheng despised him but for the sake of his promise with you he didn't start any fights,

Dre asked how old are you and Cheng answer for you, "she's 12."

You corrected him by saying you were now 13,

This made Cheng realise, "I missed your birthday..? Why didn't you tell me?"