Dean is concentrating on cleaning his guns with his little tongue poking out between his teeth while Cas is trying to talk strategy with him but he's getting increasingly stilted and tense, and then suddenly Cas is right in his face like "Stop. Doing. That. We need to focus on the mission." And Dean is like "???Gun maintenance??? Some of us don't have a fancy soul knife, dude. When's the last time you sharpened your blade, huh? Don't come for me just because you let your little weapon get rusty. Back off!" Not knowing that 'sharpening your blade' and 'weapon' are soldier angel euphemisms and he basically just called Cas worked up and small and Cas is literally shaking with barely repressed horny rage and then Dean smirks at him and is like "What? You don't know how? Need some help?" and a lightbulb pops above them and Dean is like "Dude??? Wtf?" but Cas is already whooshing away in a panic because holy shit he Should Not be losing composure like that, Dean's tongue is So Pink, there's something Wrong With Him.... What if Dean actually held his angel blade? No! Focus on the fucking mission...