"to make sense" = to say something 'rational' or something that holds truth So: "You guys are making no sense at all!" means that they are not being rational. It can also be used to show that you don't get what the other person is trying to explain. But only when the other person is really confusing you. Like: Person A: Okay, then we just have to put the yellow one in the black one, flip the switch, put the red one in the green one, turn it over, check the dots, switch it on, turn it upside down. Then we just put the E=MC2 in the shizzle and turn it so it becomes the nizzle. Then we break it, fix it, click it and upgrade it. Person B: You're making no sense at all! (or: You're not making any sense!)