The Wedding Blackening
There still exists within the islands a pre-wedding tradition simply referred to as "the Blackening".

The Blackening is a fairly rough ceremony in which the groom-to-be is waylaid by his friends. He is stripped (winter and summer!), bound and "blackened" using a messy mixture that usually contains treacle, flour and feathers. The unfortunate groom is then paraded around on the back of a truck, while his comrades make as much noise as possible by blowing whistles, shouting, beating sticks, banging drums and generally creating a din with anything they can lay their hands on.
The parade through the streets can last a few hours and it is not uncommon for the party to end up in the sea.

The sight of a blackening in full swing is usually something that causes visitors to raise a quizzical eyebrow. The tradition described in recent years by the Sheriff as an "accepted breach of the peace."
As to the origin of the Blackening - that I cannot say with any degree of certainty. An interesting idea is that the current Blackening ceremonies may be a corrupted variation of the old feet/hair washing traditions, the purpose of the Blackening being to ensure the groom is dirty before the washing takes place. The washing element has perhaps been forgotten over the centuries - unless, of course, we can count the unfortunate groom's dip in the cold sea water. However, now the aim is simply to get the groom as messy and drunk as possible. 

The general din created during the Blackening may also have some connection to the tradition of noise-making common not only during the Wedding March but at other Orkney festival times. In these cases the noise was thought to keep the trows or fairy-folk at bay, otherwise they might attempt to spirit away the bride or groom.
In the realms of pure speculation but could the Blackening itself be symbolic of such a fairy abduction? It is highly unusual for a groom to go to his Blackening willingly.

Off course, at the end of the day, one is also left wondering whether the noise generated is simply another way of humiliating the groom and ensuring as many people as possible see him in his sorry state. 

culled: Orkneyjar- Orcadian wedding traditions