awesome 
i have several times heard a “general incompetent cock up” being called “a brittas head moment”
An attempt at some Wintermark phrases:
“Brytta’s Bones!” - analogous to “Great Scott!” or “Blood and sand!”, an expression of wonderment, exasperation, or otherwise attempting to find words for the incredulous (such as the incredulously stupid). “Did you see that? Brytta’s Bones, he could have killed us all!”
“Salty” - A phrase coined by my pal from wintermark (who isn’t on here), to describe a trader he spent a lot of time with. He called him Salty because his trades left a bitter taste in your mouth! As that character is now retired, I think it’s a great one to open up to wider use. “That armourer is Salty. You’d be better off with the Navarr down the road.”
“Channeling” - someone who is talking nonsense (or breaking character!). “Oda, you’re channeling again…”
“A Marcher’s Promise” - to describe a bargain in which the promisary party delivers something other than what was expected, due to their specifically not mentioning that they wouldn’t. For example,
i) “What do you call this, you promised me a throne for that information!”
ii) “And here it is. It’s very comfortable, my old man used to whittle by the fireside on this thing. Thanks for the tip neighbour!”
i) “This is a bloody marcher’s promise, this is…”
So-named after hours of trying to coax the location of a printing press out of many, many marcher suspects: “For a crown, I’ll tell you who it wasn’t!”
“A walk with an Orc” - to teach someone a lesson in an underhanded way. “That maggot needs a walk with an orc, if you ask me.” Analogous with “Take him down the alley”.
“Frosty Fingers” - someone around whom items tend to go missing. So-called because frost binds things together and can cause flesh to adhere to metal. analogous with “Sticky fingers” or “Five finger discount”.
I tend to use “Throne and Virtues” in the same cadence as “for fuck’s sake” - ‘Throne and virtues what’re you doing that for?’ etc.
Horse trading maggot?
Cannot adequately express my love for “Dawnish Leave”. It’s funny 'cause it’s true 
[quote=“Big Bobby”]The talented Brian Wells over on the Marches Facebook group posted a whole load of marcher specific phrases before Event 1 last year. Here are a few of my favourite
[/quote]
As a riposte to the League gags,I’ll mention that I have heard people say to muddy filthy people coming back from battle: “Oh dear, you’re looking a bit Marcher; best change.” 
We have a couple of Orc expletives that we try and use.
Plough - (Fuck) - Why don’t you plough off back to Varushka
Chains - when something is totally wrong/bad - ie : This is utter chains
I’ve started using “by the virtues” or “in the name of all that is virtuous!”.
Nice and easy blasphemes right there!
Having crossed this problem in the field i found myself muttering “Virtues and vices” for quiet expressions of shocked disbelief
It’s not exactly swearing, but I became a fan of the phrase “The teeth are about to hit the pavement.”
I wish I’d seen this before last weekend 
A Leaguey one - specifically Holberg since my character and that of my SO are from there: We were passing Dawn’s “Glory Pit” or whatever they call it, and SO came up with “For Glory’s sake!” Will be pinching for future use 
Wintermarkers believe that birds carry the souls of people to and from their bodies when they are born and die. The more powerful/important that soul is, the more majestic the bird.
‘Sparrow child’ has become a firm favourite to describe anyone who might think they are important, but really is not.