Taylor Swift Is Scared of April Fools' Day

Taylor Swift in the press room during the iHeartRadio Music Awards held at the Shrine Auditorium in Los Angeles, California on March 29, 2015. 

Taylor Swift wants everyone to be on guard today. It's April Fools' Day, the most dangerous day of the year. 

Note to Taylor's Instagram Posse: She's looking at you. 

Swift wasn't the only celeb having fun on Twitter. Sam Smith tried out his own April Fools' Day prank for fans.