Heffalump is an endless honeypot that gives malicious bots nightmares. To use, in your robots.txt tell robots not to go to a certain URL, which heffalump is reverse proxying. Any web agent that does go to the URL will receive an endless stream of random data, which will overflow its memory and/or storage if it doesn't have a max buffer size set or at the very least severely waste its time.
The source of the honeypot data is [Once On a Time](http://www.gutenberg.org/files/27771/27771-h/27771-h.htm), one of A. A. Milne's most beloved and most public domain works.
Live example: <ahref="https://heffalump.herokuapp.com"rel="nofollow">Do not follow this link.</a> It will flood your browser's memory and likely cause a crash.