In Japanese, sometimes I come across words which don’t sound Japanese at all, and I am not talking about katakana words. I think I’ll start noting them down, just for reference.
The most recent of such words, though I’ll have to check the accuracy of the word, is ある程度 （あるてえど）. 程度 （ていど） means ‘about’, but what is more interesting is the sound of the word. To me it sounds Italian. After asking a Japanese friend they told me that altogether, ある程度 means ‘up to around that much’ or something to that effect.
There are other examples, but not many come to mind right now. Oh, how about ～ぱなし。That definately doesn’t sound like a typical Japanese word.