[header] How to troll your friends [title] Send a " text in progress " gif. [step] Many phones display an ellipses when you're typing a message. You can download a gif of an ellipses online, usually through an app store. 
A great way to troll your friends is to text them something exciting and, when they respond, text them a gif of the ellipses indicating you're typing. Leave your friend waiting anxiously to see your response.