Happy April Fools Day, Trekkies! According to the Star Trek Wiki, the holiday has only been mentioned once throughout all of the Star Trek movie and TV shows in existence. 

«In 2367, while discussing the subject practical jokes with young Willie Potts, who had become ill as a result of a joke played on him by his brother Jake, Beverly Crusher made the comment that «everybody’s played a practical joke on somebody.» Willie, however, insisted that he never did, not even on April Fools’. Beverly couldn’t believe that he had never «pulled something» on April Fools’ Day, to which Willie replied: «What for? It’s never funny to the one getting fooled.«»

Although Willie Potts never pulled a prank, I can imagine other Star Trek characters who would’ve thrived during April Fools. It would be pretty near impossible to prank Spock, but I’d like to see someone try to do so.