The world will be less intresting without stereotypes, it adds more flavour in our relation with our fellow folks. From the market place to office, from school to even churches; it is a norm.
Stereotypes has to do with generalization without prior process of analysis.
It originates for a sole purpose; the simplest way to explain something cos it is very easy to stick.
Stereotypes cannot give someone the opportunity to prove otherwise, it comes out plain as if it is the gospel truth.
Well, lets have a look at some of the common stereotypes that i have come across:

+ I'm a Government official, so i must be corrupt.
+ Lawyers are the greatest liars on earth
+ All graduates must have bribed their way through school
+ I'm the quiet type so I must be a nerd who read 24/7 and have parallel A's
+ Whites are more intelligent that blacks and blacks are stronger than whites
+ I'm a female undergrad, so i must be having s'ex with my lecturer for grades
+ All hausa men must possess a bomb in their pocket, all igbo men love money and all yoruba men are dirty
+ All trouser sagging guys must be irresponsible
+ I'm rich, so I must be arrogant
+ I'm a female who cover virtually all part of my body and wear no makeup, therefore i must be a member of deeper life
+ Dirty no dey kill black man
+ I update my facebook a/c so I must be looking for attention.
+ I'm a Man U fan so i must hate anything that have to do with Chelsea including dry gin!

Well these are the ones i've come across, if you have more, you may add