When you use the search form on this site, whether it's the one at the top of every page or the one to select an entry on the "Upload an Image" page, certain entry names can break the menu. We know the % symbol does this, and other characters that are reserved in URLs might have the same problem.
When one of the top 10 search results contains a % in its name, the autocomplete script will mess up, not displaying that result or any of the following ones. For example, when you search for "mad", only 4 results are displayed even though more than 50 entries match that pattern. This is because the 5th result it "200% mad", which breaks the script. If you search for "200", then no results are displayed because "200% mad" is the first result.
This can make image uploads frustrating.