Why to Exeggerate ?

why do people show off ,that too in front of the lower strata people ?why ? why ? why ?
May be because the one who is at par to them dosen't entertain them or it dosen't bother him/her.
lot of people have this habbit to exeggerate things and events which glorify them.i know a silly story about exeggeration which follows...

 Some years ago next door's dog attacked my little boy so my dog attacked that dog. My dog is five times the size of her dog that is young - fully grown but not a puppy. This happened in my garden - I saw it with my own eyes. I got my little boy inside and shouted the dog off and she obeyed and came inside. Before you know it word has got round that my dog went ballistic and attacked her dog for no reason and she had to spend hundreds of pounds at the vets. She was also telling people not to let their kids come round to my house cos the dog would attack them. I went to school to pick my son up only to be confronted by all her cronies that I had a dangerous dog that should be put down. I put them all straight and put her on the spot. Her dog had no injuries either so where did the vet story come from?

I really can't stand people like this. I wouldn't trust that woman to tell me the time. Thing is she's like this with everybody.

Why do people do this kind of exeggeration of truth?