Supposedly there are over one million words in the English Language. We trimmed some fat to take away really odd words and determiners. Then we grabbed the most popular words and built this word randomizer. Just keep clicking generate—chances are you won't find a repeat!
As an exercise for English students, generate a list of ten random words and have the student write a story that incorporates those words in the order they're generated.
You could also take the hard work out of playing MadLibs but for that you'll need to separate out the parts of speech. There's generators for each one, just jump over using the options below.