A word used to display feelings of hate and animosity towards someone. Similar to calling someone a rasclat or a wanker. The word has the same effect as a swearword basically to tell someone they are a dick or to fuck off.
Jerome: Give me that money G
Tom:Shut it you fassy clam.
Someone who looks after themselves and is incredibly vain. They tend to be young and have a clean cut appearance often wearing designer labels. In the UK a typical pretty boy would wearing the latest designer clothes have and have a mohican or spiky hair. Generally the UK version are unintelligent where as the US ones rich and tend to have an education.I would reject some of the previous entries for pretty boy referring to ll cool j and usher. Not meaning this in a racist way but i think wouldn't think of either of them as pretty boys as white guys are generally thought of as pretty boys. Also rnb and hip hop artists try to act more like bad boys which is the opposite of what a pretty boy is.
Zac efron and the jonas brothers are textbook examples of pretty boys.