Definition: Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.
Input: They claimed to be playing an April Fool's joke, but most people who saw the signs were unfamiliar with the phrase.

They said it was an April Fool's joke, but most people who saw the signs didn't know the phrase.