In the Houghton Mifflin anthology I asked students to read all the pages with riddles and jokes in book 1.2 (there are several short selections). We talked as a group about what makes a good joke or riddle and the format they are written in.
Groups of 3 students had to come up with 2 riddles. They could use either Educreations or StoryBuddy to tell publish them. It was pretty evenly divided as far as which app was chosen.