The english language is characterised by its enormous vocabulary, where many words are synonyms. Take the following: ire, wrath, anger, vexation... English is a variety of other languages (Norman French, Viking Norse, Danish Norse, Angle/Saxon/Jute German, Welsh, etc etc) slammed together repeatedly over centuries until they stick into one big lump with the joins only partly visible. This makes it a wonderful vehicle for poetry and prose, especially playwriting. It is a richness missing in many arguably "purer" languages.

And so it is with phrases. There seems to be an almost built-in tendency among Brits to use slang terms and jargon, especially where this closes the language to outsiders of a given social group, hence the tendency of teens to keep dreaming up new ways to prevent old duffers (mainly parents and other authority figures I suppose) from understanding them. Every generation produces yet more new ways to say the same things. The supply of slang words and phrases appears to be inexhaustible.
Many phrases stick and "catch on" and become part of the language forever.

Sexual euphemisms are the most satisfactory to innovate, and the more arcane and obscure the terminology, the more distant it is from the "proper" terminology, the more pleasure one derives from inventing, or maybe even just using, a given phrase.

Add to this a long tradition of bawdy comedy in Britain, and suddenly a phrase like "how's your father" becomes lost in an ocean of expressions that have similar utility. Visitors to the arrse.co.uk website's forum of unrestricted-dark-humour discussion at http://www.arrse.co.uk/cpgn2/Forums/viewforum/f=12.html will, after an initial period of being astonished at the depravity of the Britsh armed serviceman, find a dazzling wealth of euphemisms of such vast variety that would, were such phrases worth money, require the attention of a whole board of secret swiss bank accounts.

sounds like something one would say after a revenge lay for an ex to his son but thats just me

quote Justice Oliver Wendell Holmes-"A word is not a crystal, transparrent and unchanged, but instead the skin of a living thought that may vary greatly in color and conent according to the circumstances and time in which it is used".