If you're happy with grayscale, there's a different trick that works natively on Twitter. Don't click on homu!pic.twitter.com/ET0P1czAT8
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
Although it does have some hilarious results
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.