A text response, when you are too lazy to actually express how you are feeling or when you don't think somethings funny but you don't want to hurt their feelings.
Person 1: "HAHAHAH, OMG! Knock Knock."
Person 2: "Who's there?"
Person 1: "Joe."
Person 2: "Joe who?"
Person 1: "JOE MAMA!!!!!!!!!!'
Person 2: "lol"