What I normally post here are things which are a bit more polished, a bit more finished and together that this, but this thread on Imgur by user Looked4LoveInAlderaanPlaces (terrible, terrible pun mate) called Nature, You Scary is really rather neat.
It all stems from a suggestion to come up with a scenario where aliens invade earth, effortlessly wipe out human defences, only to run into major issues from the local wildlife.
Or, to give you the suggested tag line:
They were expecting military resistance. They weren't counting on bears.
It's written in individual short bits, by different authors, in slightly differing styles, with no editing to hold it together or clean up the style (or the typos, for that matter), but it's hugely entertaining, and well worth reading.
The title itself is part of an Internet meme, and so is the picture on the right. Isn't this just the cutest little alien?