Hey UK,
Many, many years ago, there was a group in (I think) London with a website about something they called anarchitecture. Had a lot of stuff about weird posters on city streets (we called it 'culture jamming' back in the day), repurposing public spaces, etc. Lot of early 2000s punkesque humour.
Does anyone recall this group and any details? Trying to track down the old website (e.g. mentions floating around in old articles with a link I can toss in Wayback, that kind of thing), but only really recall the term 'anarchitecture' and the fact that they had a project called NOT CRICKET (conceit was challenging MPs to a game of cricket in a government-owned outdoor space). Web searches have been less than helpful so far, mostly bringing up architecture businesses. Anything may help, even just recalling names used for other projects.
Edit: changed 'reality jamming" to 'culture jamming', which is the appropriate term and the one I think said group used. Another memory: one of the stunts was setting up desks and/or mini-parties in parking spaces.
I hadn't heard of that particular group before, but your post called to mind BLDGBLOG by Geoff Manaugh which covers that type of stuff with that sense of humour.
Sure enough, one of his posts references anArchitecture and has a link. Sadly, looks like the site is gone but hopefully this helps you find an archived copy.