Pretty obvious:
http://fashion.telegraph.co.uk/galleries/TMG10035532/Dress-Down-Friday-a-mans-guide-to-what-not-to-wear.html
Good to see jeans and jacket gets a thumb down.
Some funny stuff. I disagree on a couple points though. Good thing I'm in the construction biz and self employed.
I've never given the reasoning behind the 'dress down Friday' trend much thought. Was it an HR ploy to increase employee productivity by blurring the distinction between work and home and leisure, or just an attempt to get men to have a bigger wardrobe?
It was from the USA originally, but it is practically redundant now with the dress down etiquette practically a given all week long in a lot of industries. But the intention like Sammy states, was an attempt to blur the distinction and rigidity of work.
Of course, Friday in my industry was always noted as being Poet's day: Piss-off early today.
Wasn't it an attempt to try and appropriate some of the 'whizz bang' of Silicon Valley?
However, what seems to work in Silicon Valley won't necessarily work in a conservative Investment Bank.
Long before dress down Fridays were the thing I understand that in design offices in London it was commonplace to play various board games on a Friday afternoon. This was a way of generating team spirit and it helped in winding down for the weekend. Lunchtimes were spent in the pub so maybe it also helped in avoiding Friday afternoon cock-ups. I worked with teams of old school draughtsmen and women (tracers) who swore this was true and many missed the game playing. We all still went to the pub, including the bosses, after boardgames fell out of favour.
Perhaps Reckless Reggie can throw some light on this?