Morsa, Spanish for walrus. It just rolls off the tongue (not unlike a walrus would).
farkakta
pantuflas
I like non-English words which are compounds words for which in English we have a simple word, and yet the compound in the other language is very logical, however funny when literally translated.
For example, in Swiss German, the word for potato is Erdäppfli, literally, “ground apple.” In Korea, they don’t have opossums, so the word for that animal is 주머니쥐, or “pocket rat.”
To add to the list of curses, I’ll add ‘zut’ to the list (French for ‘damn’). It has a nice sound to it, is the only remotely naughty French word I know, and I have fond memories of my eighth-grade teacher using it after messing up a student’s name 
The Hungarian word Tessék is used as a gesture:
<knock on door> “Tessék, come in.”
<phone rings> “Hello, Tessék”
<I’m handing you something> “Tessék” (here, take this)
<I’m selling tomatoes>“Tessék, tomatoes!”
<I’m seating you at a restaurant>“over here, Tessék”
<I didn’t hear what you just said>“Tessék?” (please repeat yourself)
It is the third-person, plural, definite , conditional-imperative conjugation of the verb Tetszik - “is pleasing”
Oy.
myggigt
An adjective that means “mosquito-ey” (as in, lots of mosquitoes about) in Swedish. It is the perfect word for summer nights in New England. Like “buggy”, but let’s be explicit here – these things are biting me and they need their own word!
Embonpoint - French for “in good condition”, but used to describe people who are attractively plump.
VCNJ~
(German): doppelganger
(French): merde
(Yiddish): schmuck
(French): tet-a-tet
(Spanish): fandango
Pamplemousse. French for grapefruit.
I’m gonna want to make sure I say that right. Can you help me out with a little fo-NET-ik FRAHN-say? I’m guessing em-bon-PWAHN, but don’t trust myself.
Oy is not a word. Oy is a vocabulary
Does Avada Kedavra count? No?
Okay, how about chupacabra, and the Moroccan word habibi, which is a term of endearment, sort of like “my little one” or “my love.”
I’m also partial to foreign versions of “fuck you,” but while I can say them, I can’t even begin to tell you how to spell them!
When I was in Finland, I encountered the word loyly (the y is pronounced like u in French tu), which was basically untranslatable, but had to do with the feel and ambience of the sauna experience. I think.
I’m going to have to remember that one. Vous êtes embonpointe. 
Glockenspiel. I just like the way it sounds.
Well, even though Airman won the thread already I’ll post my fondness for the German word einfach. It is fun to shout because anything you shout in German makes you sounds like a mean sunuvabitch. It means simple.
“Quelquefois.” French for “sometimes.” For some reason, you say this to some dogs and they go nuts. Try it on your dog.