kumarreksituteskenteleentuvaisehkollaismaisekkuudellisenneskenteluttelemattomammuuksissansakaankopahan

The word was created my prof Artturi Kannisto, a linguist, in 1941, if I remember correctly. It is not a compound word, but uses suffixes, which are very common in Finnish. All the imaginable (no, not all) are combined in that one word, and though it is grammatically correct, it is over-over-über-artificial and next to incomprehensible -- or completely incomprehensible, to be honest.

If it means something, the meaning is extremely convoluted.