I love this - sadly I think it's happening in the US only.
This campaign will run on 29th September, to tie in with the bizarre 'Talk Like A Pirate Day' which was created in 1995:
"In celebration of Talk Like a Pirate Day, which falls on September 19 this year, Krispy Kreme is inviting customers to dress up in their finest pirate gear to receive one dozen free original glazed doughnuts. Qualifying costumes must include three pirate-themed items, such as a bandana or eye patch.
If individuals do not own such gear, they can simply visit a Krispy Kreme store to access the chain’s custom Snapchat geofilter, which can be used to digitally adorn their outfits.
The filter features a pirate hat, parrot and sword.
Consumers must then show their Snapchat selfie with the accompanying filter to any in-store associate to receive a free set of a dozen original doughnuts."