One of my former customers had their former webmaster reuse snippets of HTML from their site and one of the IMG tags on his site pointed to an image on my former customer's site. We weren't using that graphic any longer so I replaced it with a parody of the product he was offering. It was almost a year before he corrected his IMG tag.

The funny part is that product was the reason he got fired by my customer and why I took them on as a customer in the first place.

Back story:
My former customer has a company selling custom women's wigs. The old webmaster wanted to offer a video of how to cut and style a wig for which he would get a commission from the owners and from the video producer we suspect. According to my customer the video was poorly made and full of erroneous information. So my customer told the former webmaster that they wanted nothing to do with the video and could not endorse it. The dumb part was he already signed an agreement with the video company and was offering it for sale on the website under a sub-folder. It was not tied into the rest of the website. Don't ask me why he didn't put it on his own domain.
I saw the video early on but didn't know they weren't actually selling it themselves. They had hired me to backup their website without their old webmaster knowing. So I'd ftp into their server and make weekly backups.
Anyway a customer called and wanted info on the video which alerted the owners that he was selling it on their domain. So he got fired.

Because he reused HTML snippets when offering the video on his own domain, the IMG tags pointed to my customer's website like I mentioned.
Avoiding the actual name of the video it was something like Hair for You. So I replaced the image of the video box with a picture of a woman in a pink bunny suit with rabbit ears. It took the guy almost a year to notice the bunny image and fix the IMG tag.
The guy was pretty incompetent. I don't think he ever did a view source on any pages. Some of the IMG tags on the site pointed to files on his local C: drive. So he couldn't see the problems from his computer. For everyone else they got "the webmaster is an idiot" red x.
I had to scrap their entire website and start over it was such a mess. Over 300 static HTML pages done in MS Frontpage. I replaced what he had with a custom shopping cart system only needing 11 or so pages. Eventually they were able to offer over 1500 products with no hand coding of anything. Just add the products to the database and upload the product images. They were so happy. They could even change any or all prices with a single admin page. "Raise all prices 10%, Click" What a radical difference in the day to day operations. Their sales went up 20 fold and they went from 1 part time employee to 2 full time employees. So that is 5 times the efficiency.

I'll bet the guy at first thought I'd hacked his website. What was he going to do? Sue me for his incompetence? Fun times.