Fascinating thread this...
I haven't been to many weddings at all as I kept moving countries in time to miss wedding seasons. But some peculiar moments:
In Germany, some people treat the eve of the wedding as 'polterabend,' lit. 'thundering/growling' evening, and the tradition is to break old crockery. I once went to a wedding in a region that used to be a centre of china production, and both bride and groom's family had connections to the industry.
Guests brought out crates of crockery, seemed like dozens of them, and just emptied them into the bride's parents' yard. Bride and groom waded ankle deep in shards, wielding brooms, patiently pushing the shards into heaps while their guests were nursing beers. They seemed quite unperturbed by this and the actual wedding was fun.
Then there was a wedding in Scotland where the groom took some of the guests on a hiking tour the day before. Wildly overestimating the guests' mountaineering skills and underestimating the terrain. They were brought back by a rescue crew halfway through dinner, looking absolutely dead on their feet, one woman leaning on a rescuer. To this day, I haven't seen people look more exhausted.
All recovered overnight and the wedding was lovely. I suspect the bride had an, ahem, word with the groom though.