Recently, while listening in the background to a French podcast (http://www.dailyfrenchpod.com #1914, Villes anglaises (UK cities)), my mind partially registered the word for mosquito, a word I didn't recall ever having learned. Some time later, relying on my audial impression (mistaken, as it turned out) of how it "should" be spelled in French, I searched for "mousquite" in my Larousse English-French dictionary app, but couldn't find it. I went back to the podcast and discovered my spelling-impression error.
The positions of "qu" and "t" are swapped between English and French: mosquito / (le) moustique
I imagine it may be relatively rare that consonants are so transposed.
I also looked up la moustiquaire (mosquito net/screen), which, with respect to consonant sounds, has a similar transposed position relationship to le mousquetaire (musketeer), plus a mildly different middle vowel sound.
