I have nginx reply with a 418 page to bad bots requests. Funny easter egg. As a bonus, that makes nginx avoid checking the filesystem for inexistent files, and makes filtering logs easier.

Nginx config snippet:

  # Nothing to hack around here, I’m just a teapot:
  location ~* \.(?:php|aspx?|jsp|dll|sql|bak)$ { 
      return 418; 
  }
  error_page 418 /418.html;