First of all, most importantly, you need to send an anonymous text message. You also need a plan for your April Fool's text prank. The most important factor for success is that the recipient initially thinks the message is real. See also the April Fool's Day prank examples on this page. Secondly, it is important that, once the prank has been sent, at a certain point, you do tell the 'victim' about the prank. Untill that moment, for more entertainment, it is recommended that you are with the person the moment he or she receives the text message. You can set the timing of your text prank on this website.