I was looking for childrens beds recently, and I stumbled across Children's Bed World. They have a nice, database-driven site where they can automatically calculate your savings against recommended retail price (RRP). Unfortunately, their database records all the prices, including the ones they're marking up.
Here's the "Verona" trundle bed or "guest bed" as they call it. The first thing that got my attention was the "save -11%" on the overview. Sure enough, when you click on it, you get a bigger view that makes it totally clear how much you're NOT saving. Original page is here.
That's not the only one like that. I went to "metal beds" and sorted them by price, highest to lowest. I found the "Amelia" bed frame was offering negative zero percent off. Huh? Yep, it appears the recommended retail price (RRP) is £149.95, but with them you pay only £149.99.
The code is obviously broken for displaying the discount. It is supposed to tell you you are saving -£0.04, but it prints it as pound, decimal, negative 4. That's strange no matter how you look at it.
I could probably find more of these, but that was enough. Pretty amusing.