If you haven't heard about the Seething Sardine Festival or associated events, where have you been? Seriously?
Here's a quick catch-up.
Made-up nonsense fables about giants and goat-boys treated with utmost reverence as if they are gospel truth.
A wistful look back at the past when communities came together.
Related: 16 brilliant things from the Seething Festival in Surbiton
Thousands of people from across London trekking to suburban Surbiton to take part in the crazy community events which have included giant games of mousetrap and pop-up pirates, a ski Sunday when competitors tie ice cubes to their feet, and steam punks and children in cycle races on Penny Farthings.
It's kind of unusual but it works - devotees get their community fix, and the creativity and imagination of the arts crowd gets an outlay.
It's so successful universities are studying it and Boris Johnson is trying to bottle it and use it to help struggling high streets.
The latest event is the Seething Sardine Festival - this one is about the fiction that sardines used to swim free in the Thames downriver of Kingston and was held on a sunny but windy day in May.
So, is it London's strangest fun day? Decide for yourself by visiting the Seething Wells website and coming to an event.
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