answer: Ms. Wang gives Tom a billfold as a birthday present and tells him in China people don't open it right away. Tom makes a wish and will cut the cake.
documents: #Person1#: Happy birthday, Tom, This is for you. 
  #Person2#: Thanks, Ms. Wang. 
  #Person1#: You know, in china, we usually don't open presents until the guests have gone. 
  #Person2#: Really? I've already opened this one. Say! This is swell! Look, Mom, a billfold. 
  #Person3#: It's very nice. You really shouldn't have done it, though, Ms. Wang. 
  #Person2#: Ms. Wang, it's a custom to bring a birthday gift as you have done. Is it the same in China? 
  #Person1#: Yes, it is. 
  #Person2#: Well, dinner is ready. Please come to the dining room. 
  #Person1#: Oh, they all went out! Did you make a wish? 
  #Person2#: Yes , but I doubt if I get it, I haven't yet. 
  #Person1#: Where did that custom come from? 
  #Person2#: I've no idea. 
  #Person1#: You cut the cake and pass it around while I go get the ice cream. 
  #Person2#: Would you like some more coffee, Ms. Wang? 
  #Person1#: Than you. But I'll take it black this time.