Peel banana and break it into a few pieces. Mash it with a potato masher until it is mushy with no lumps. Add in the yogurt and coconut and mix. Spoon mixture into a 5 ounce paper cup. Put a small spoon or ice cream stick in the middle and freeze for at least 1 hour. When ready to eat, hold igloo by stick and dip cup into hot water. Count slowly to 5 and slide igloo out of the cup.