answer: Johnny calls Della and asks her to throw Gerald a surprising party with Tony and Amy. Della hesitates at first because of the work but then agrees.
documents: #Person1#: Della, this is Johnny.
  #Person2#: Oh, hi Johnny.
  #Person1#: Hi. Hey, this Wednesday is Gerald's birthday. Tony and Amy suggested that we throw him a party. Would you like to come?
  #Person2#: This Wednesday? What kind of party?
  #Person1#: A disguise party.
  #Person2#: Sounds like fun. Where will it be held?
  #Person1#: At my place, we're going to decorate the house tomorrow afternoon.
  #Person2#: Does Gerald know about the party?
  #Person1#: No, we want to surprise him.
  #Person2#: I'd love to come, but I'm up to my ears in work. I'm not sure whether I can spare an evening.
  #Person1#: Come on Bella, I know you like Gerald, and Gerald thinks highly of you, but you've always been busy, and he's never had the chance to ask you out, you might as well give him an opportunity.
  #Person2#: So, am I the surprise of his birthday party?
  #Person1#: You could say that.
  #Person2#: Alright I'll be there, I guess I better buy him a present this evening.