So I read this fic awhile ago, and I'm pretty sure it was on AO3. In it, Dean kept making his voice deeper and deeper in an attempt to go deeper than Castiel, and he kept telling himself it was for that reason, but he was really in denial about how much Castiel's voice turned him on. It was a very humurous fic and super cute. I've been trying to find it for forever, and I know I didn't give a lot of details, but if anyone recognizes it I'd be super grateful!