I use too much english in my daily norwegian. It's not exactly slang, rather quotations and words that I don't recall the norwegian word for in the moment; It sounds stupid.
The only other languages I know some of except english are spanish and japanese (just about the bare minimum to be able to read through Harry Potter in spanish , and some shorter stories like 夢十夜 and 藪の中 in japanese at least). However, I never use those in my daily language.
Some norwegians use a few german words as slang (klein, spaß, scheiße), espesially in the area around the capital (Oslo). There's also a myriad of different dialects and two different written forms of the language in Norway, so I guess one could take several words from there(f.ex. kvervelvind instead of tornado, flogvit instead of geni(genious)). Anyway, so far I don't have much foreign slang in my language, except for the english mentioned in the first paragraph.