Somebody posted the challenge to change one letter in a book title and ruin it. Naturally, I decided the computer should help come up with the bad suggestions.
The page has an embedded dictionary and a small JavaScript search. For each word in the title, it tries replacing one character at a time with another letter. If the result is in the dictionary, it prints a new version of the title and colors the changed word red. The title and the dictionary stay in the browser; there is no request to a service for suggestions.
It does not understand books or jokes. It just finds possible word substitutions, and we get to decide which ones are funny. I like the gap between a very mechanical search and the occasional ridiculous result. This was probably more code than the original challenge required, but that is half the fun.