Perkeleen perkeleen helvetin perse.
Funny thing, my translator gives me this as a translation: "The Devil the Devil damn it lost."
Literally, it is "Devil's Devil's hell's ass".
Also, the word TheTa learned (I assume it begins with "v") is really useful. It can be used for the c- and f-words, also in a less literal sense as a replacement for the d-word, h-word, and s-word, and it can change the modus of any verb into "aggresive". Also, it can be used as a sort of filler word like Native American "ugh" (which itself is a mistranslitteration of an actually meaningful word, oh well). Also, the youth use it as a sort of informal greeting, both when meeting and when parting.
EDIT: The v-word has almost as many uses in spoken Finnish as "bitte" has in German. So you can use it instead of "Yes, please", "Thank you", "Here you are", "I'm sorry", "Excuse me", "I did not understand", etc., or at least the youth seem to use it this way. Also, it can be added as a genitive-looking adjective to any noun.