Quite often in Bulgaria nargoni use words and phrases like these:

flea bite - "Nothing will be his"

of the pie soft - for someone who is lazy

Well, we have a problem here. Most portuguese slangs are words or modifications of one. We have a slang that actually became a very common word: você. It means you (singular) but in portuguese it should be Tu or Vós, where the hell did we here in brazil create this você, I don't know. But there are some expressions like:

Macho, literally male. In the northeast of Brazil (where I live) it is very common to call men "macho", But we don't call women females

Get your foot out of here, it means: Get the (censor bip) out of here. In portuguese: Arrede o pé daqui.

Eu to duro, means I am hard, it just means I have no money. It is weird in english, now that I wrote it

Que diabo é isso? What the hell, I think everybody knows what this is.

That is all I can think for now, there are others, but they are just too hard to explain.

There's a Finnish colloquial unit of measurement (distance) called a poronkusema (lit. reindeer pissing), which literally means the distance a reindeer can travel before it needs to pee. It's around 7,5 km, and unsurprisingly the term is rarely used anymore.

Not exactly "slang", I suppose, but an interesting local term nonetheless.