Asklemmy

English speakers always seem to like mierenneuken: nitpicking, or literally, ant-fucking.

Or maybe fokker, meaning breeder (and a famous last name; and speaking of names, we have first names such as Fokko and Fokje).

Worcestershire

I think this is specific to my own neck of the woods, but the words "pija" and "verga". It can be used in a variety of different contexts and will mean anything between the bee's knees to absolute shit.

For example, "la mera pija/verga", literally "the very dick", means "the best"; while "la pija/verga" m, literally "the dick", means "the absolute fucking worst/incapable/incompetent". "Pijin" means rave, "pijeada/verguiada" means either a scuffle that ended with one side getting beaten very badly, or something that is very hard to do.

An example of the last one: "Darle pija a Malenia, Blade of Miquella, es pijeado", meaning "To beat Malenia, Blade of Miquella, is hard".

... Lots of phallic turns of phrase. But its usage probably isn't so different to the versatility of the word "fuck" in the english language.

In English, it has to be any of the Contronyms. We have so many, and it really makes it hard for newer speakers to understand some things.

You dust a cake by adding powder, you dust a table by removing powder.
You seed a field by adding seeds, you seed a fruit by removing the seeds.

Syzygy

"Rævsnerk"

Noun: That moist substance between your ass cheecks on a hot and humidity day when you haven't showered for too long.

Ræv = ass.
Snerk = that membrane-like substance that forms on top of soups and sauces that have been left in room temperature for too long.

Some Russian ones:

недоперепил: недо - not quite, пере - overdid, пил - drank. Sounds weird due to opposing suffixes, basically means "haven't drunk enough to get completely wasted", in my circles we use it to describe displeasure when the alcohol runs dry on events we've set to get wasted all along.

опердень: Due to how it's only used in professional circles and how language is structured, someone hearing it for the first time might think it's a word rooted from "пердеть" (to fart), and based on the suffixes assume it relates to some kind of creature that farts (or get farted) all over. But it's actually a shorthand for Операционный День (processing day) which is how finance guys call their banking software as it basically replaced said processing day in their work.

Same for "опсос" - sounds like "someone who sucks all over something" but is just a shorthand for "оператор сотовой связи" - phone service provider.

تعارف (ta'arof) it is.

http://www.theatlantic.com/magazine/archive/2012/09/talk-like-an-iranian/309056/

Klabusterbeeren
Klabusterbeeren are "berries" out of cotton and hair, which you can only harvest from your ass crack.
Also known as Winterkirschen (winter cherries).

연패

Can mean "to lose multiple times in a row" (連敗) or "to win multiple times in a row" (連霸).

skookum. It's borrowed from, like, old Aboriginal trade language. It means "deal's done" - with its own hand-brushing gesture - but it also means "strong" or "resilient", I think.

And now it's almost a common 'Canadianism' -- if your Newfie buddy says " 'At's a skookum blow we gots, b'iys", you know there's a sad BC Ferry-tale on the way, and you're not getting Over tonight.

Mr. Speers you here?

Flammable, Imflammble, and Inflammable.

Asjaajaja

Weirdest

'Zuignapje' -> a little suction cup to attach things to windows.

It's not weird, and it's not my first language, but "equivocado" is one of the funnest words to say in the world.

The word 'weird' is pretty weird.

„Chrüsimüsi“ belief me or not but it means chaos

Scots - I like fannybaws.

(Vagina testicles)

Fustigate and discombobulate are a couple of my faves.