On the Internet, there are a bunch of cool images. Most people are fine if they are spread and displayed, should the proper permissions and bandwidth be in play.
However, there are those (commonly called "leechers") who display images on their site directly taken from another "Hotlinked" or "Inline Linked", using the other site's bandwidth without permission for their own purposes. Of course, when the home site find this out, it's quite easy to change the image to something else. Hilarity Ensues. Usually it's just changed to a warning against using images/bandwidth without permission, but sometimes, snarky pranks or Shock Site images ensue.
Another variant is to detect people running ad blockers in their browsers and either guilt-trip users into disabling them or signing up for a subscription if the site offers one.
This is why we have the Media Uploader.
- Saturday Morning Breakfast Cereal: The "National Organization for Marriage", an anti-gay-marriage group, hot-linked a comic from his site. The author responded by changing the image to one supporting gay marriage.
- Jason Scott, the owner of the textfiles.com domain, hosted a "Grim Reaper Holding an Hourglass" image, popularly hotlinked from MySpace (usually as a background for people's blogs), but 400 hotlinks/hour was a bit too much, so he replaced it with Goatse. He later published some metrics showing how the download statistics for the file had taken a sudden plunge.
- A 2004 LiveJournal April Fools' Day prank called "Operation: Jour de Poisson" featured a user spreading an icon in apparent support of the phrase "Under God" in the pledge of allegiance... switching the image to one supporting the exact opposite stance on April 1.
- The webmaster of Cockeyed.com has an entire page of examples of dealing with leechers. In one case, he replaced the image with a "certificate of achievement" for "amazing blowjobs" with the leecher's name on it. Another time, someone used his photo on the eBay "about me" page, so the webmaster added some text beneath that called the guy out for stealing photos and selling pirated movies.
- The MySpace page of 2008 Presidential candidate John McCain featured an update template which didn't give the requested credit to its designer, and leeched images from his site. He responded by replacing it with a fake message from John supporting gay marriage.
- The EVE Online WMG section of this very wiki once hotlinked an image to the new galaxy introduced in Apocrypha. Upon finding it hotlinked everywhere, the author changed it to an image begging for the Naglfar-class Dreadnought to be buffed.
- The evil forces of Anonymous used this tactic against the Guardian newspaper when it leeched a picture taken at a protest against the Church of Scientology from Britchan. They responded with Goatse. The exact course of events is documented in a YouTube video.
- iMockery would replace the hotlinked image with an obnoxiously long gif that stretched the browser to massive proportions. The text would chide you for hotlinking.
- Seen here is Cracked's example, where a Spanish-language website had taken their entire article, including hotlinked images.
- When Something Awful's paywall went up during the finale of the Danganronpa: Trigger Happy Havoc Let's Play, they discovered people on Tumblr were leeching images, and redirected it to an image of a girl lifting a table in rage with the tagline "STOP LEECHING YOU FUCKS".
- Jameth, a user of Encyclopedia Dramatica, keeps an eye on his bandwidth and if enough people hotlink to an image, he'll replace it with a photo of four black men being lynched with the suitably offensive message "NO NIGGERS" printed on it, invoking the stereotype of black people stealing things. It's bad enough that it won't even be linked to here.
- Joemonster.org, a Polish comedy website, did this once. Another humor website hotlinked to a funny video on Joemonster's server (and even copied Joemonster's description), so the site administrator replaced it... with a hard porn video.
- The Oatmeal had the Huffington Post hotlink to some of his images. He first hit them with a polite letter asking them not to along with a graph showing his monthly bandwith costs. When that failed he swapped it for "a butt and a pee pee".
- A variant: When a tweet by a Donald Trump supporter was quoted in a CNN article, the user proceeded to change his Twitter username to "CNN is Fake News ;)" Due to the way tweet quoting works, the phrase ended up being displayed in the article as a result. The article was edited to remove the tweet... then another Twitter user quoted in the article did the same thing.
- Ex Astris Scientia was infamous for having an anti-hotlinking filter so trigger-happy that not only could it happen with normal, not-showing-the-image, links to the image (not unknown elsewhere, and not entirely unreasonable given how some bots work), it was not unknown for people browsing the site itself having images blocked by it.