Theme Parties

Theme parties - I do wonder, who was the first person to actually do this. Perhaps it's the boring nature of having a gathering where people gather and mill around with drinks in hand, exchanging the latest gossip. Which is actually not a 'bad thing', since gatherings are for people to gather around whatever.
At the end of October, some adults would gather around for a Halloween party - dressed in gory outfits, but still milling around and exchanging statements. Some functions would request for a black-tie affair - but guests still mill around sharing conversations. If the whole idea is just to mill around and have conversations, then what's with the dress code?
It's not just here, where people need to be told, specifically, what they should use as their party gear - because locals being locals, dare turn up in church, for example, in their flip-flops and beach wear. The whole partying world does have these parties by theme.
I only know how to dress for work, housework and work-outs (not necessarily gym attire). Whatever that falls in between is a grey area and one which my closet doesn't contain.
This year, our corporate function has a Retro theme.
I had to take half a day off to think about it, since we are working first, before partying in the evening. Almost every piece of clothing, not under 'office wear' was under scrutiny - after 4 hours, I needed my migraine sweets.
I would have attended the function, had fun, with or without a theme.
I guess, I wouldn't know why we are having a theme until this evening. Perhaps it will inject some fun, perhaps....let's see