Pronounced "shvine-hoond." German for "pig-dog." A vile insult in Germany, it has come to enjoy a modicum of popularity in the U.S., in either it's original German form, or translated to English
Schweinhund! I piss on your grandmother's grave!
You don't frighten us, English pig-dogs! Go and boil your
bottoms, sons of a silly person. I blow my nose at you,
so-called Arthur-king, you and all your silly English kaniggets.
- from Monty Python and The Holy Grail
A common misspelling of the German insult "Schweinehund" that is exclusively used in British or American movies about WW2.
In Germany itself, the word "Schweinehund" as an insult has probably been out of use since 1900 and now is solely used to refer to one's inner resistance against making an effort, even if it was for one's own good ("innerer Schweinehund").
German General in bad WW2-movie: "Ve vil kill yoo Britischen schweinhund!!"
German person in the audience, highly amused: "LAWLZ! Fail."