answer: #Person1# and #Person2# are using special ways to chat online. #Person3# explains their usage.
documents: #Person1#: What's up? 
  #Person2#: Not much. Its frezzing in Beijing. 
  #Person1#: U should come to Bangkok. We've got lovely weather here. 
  #Person2#: Great! R y inviting me? 
  #Person1#: Laughing out loud. 
  #Person2#: Be right back. 
  #Person1#: Where r u going? 
  #Person2#: Bathroom. 
  #Person1#: Ok. I'm going to go to bathroom too. Talk to you later. 
  #Person3#: When people chat online, they often shorten words. Use abbreviations, use lower case letters, and rarely use punctuation marks, especially apostrophe marks.