SITUATION:

What do you do...?

• if a person who you are talking don´t shut up: you must rease your volumen of voice and get in the conversation, make fisic contact with this person point out that you want to talk or some more polite wait that the person finish to talk and then it´s your time for talking! but if you don´t have time for waiting you should use: "why not?" the person who you are talking be quiet for hearing the end of the sentence.
  
• if a person who you are talking don´t speak: you could ask about the subject of the conversation, you could be quiet and create a need for talking maybe you or him or say to the person is not talking and he think about it.