This word can have several meaning to help defuse an argument or let some one know of your displeasure or delight. It is a word commonly shouted during a silence or in a public place to attract attention to yourself.
I can also be used when you are being told a story you are dis interested in to indicate you want the other person to shut up.
The word should be shouted loudly and in the voice of a upper class gentleman from West London.
Person 1 "Today at the library I placed a plaster over my ear after cutting it during a darts lesson.. Would you like me to expand"?