Author's Note:

I blame my friend/beta/soul sister C.C. for this. She sent me a tumblr post about synonyms (particularly butt-dial and booty call), demanded I write Cas getting confused, and voilà, this happened. Hope you guys enjoy it~

It all starts when Dean's phone rings.

He doesn't plan on answering it out of sheer laziness, disguised as laser focus on the beer in his hand. But Sam, who'd been quietly reading a book across the table, shoots him his patented Shut Up While I Nerd™ bitch face, and then Dean has no other choice.

So, really, Sam is to blame for everything, even though it's Dean's own stupid heart that jumps, his own traitorous finger that accepts the call when he sees Cas' name on the screen.

Dean curses as he fumbles and nearly drops the phone, bringing it to his ear.

"Hello? Cas? What's wrong? Why're you calling me?" the rapid-fire questions are out of his mouth before he can stop himself from sounding like a bumbling idiot.

The way Sam raises an equally intrigued and amused eyebrow at him does not help, either. Dean mouths the word 'bitch' and pointedly flips him off. Sam immediately mutters, "Jerk," but he throws his hands up in mock surrender and returns to reading his book when the other glares at him.

His attention now off of his brother, Dean realizes that Cas hasn't answered him yet.

"Cas?" he repeats, wetting his lip. "You there, buddy?"

There's another long pause before the staticky hiss of shuffling from the other end assaults his ear.

"Oh, um," Cas starts awkwardly, but says nothing further.

"Cas?" Dean repeats for the third time, actually concerned now, and ignoring the curious look Sam gives him. "C'mon, talk to me. You're not hurt, are you?"

"No!" the ex-angel blurts, sounding flustered, and Dean flinches at the abrupt increase in volume.

"You sure?" he clarifies, switching ears with a scoff. "Hell, if you're not, I might be now. You almost blew out my goddamn eardrum."

"Sorry. And yes, I'm certain that I haven't been injured, I just-" Cas sighs, then starts over much more calmly. "Once again, I apologize. This is a booty call, Dean."

The phone slips out of his fingers and clatters to the floor. Dean stares at it, too shocked to respond to Cas' faint but still audible voice, repeatedly calling his name.

Sam laughs, the bastard. "What did Cas do now? Adopt eight kittens and decide they're going to live in the bunker with us again?"

"No, and shut up! We only have three now. He..." Dean swallows, shaking his head to clear it. "Okay, I think I just got a booty call."

"No shit!" Sam exclaims, shooting to his feet and wincing as the chair screeches against the floor. "From Cas?"

He walks around the table to stare at the phone with Dean. For a moment, it's so silent that they can both hear him, still on the line - still calling Dean's name.

Dean pinches the bridge of his nose. "What the fuck am I supposed to do?"

Sam smirks and it's as infuriating as ever. "Accept it?"

"Hell no!" Dean yells, ears turning red as his voice cracks.

His giant brother crosses his arms, cocking his head in an 'oh, really?' kind of way. "You know you want to, Dean."

"This is Cas, Sam." Dean's eyes dart about the room nervously. "How the hell does he even know what a booty call is?!"

Sam blinks, and then his eyes widen in understanding. "Oh man, I think I know what's going on."

"Please," Dean says dryly, "enlighten me, oh Nerdy One."

Sam rolls his eyes and picks up the phone, handing it to Dean.

Dean shies away from it. "No way, man. I can't-"

Sam shoves it forcefully into his hands. "For god's sake, Dean! Just ask him to clarify and you'll see what I mean for yourself. Put it on speaker; I want to see if I'm right."

With one last skeptical glance, Dean puts the phone on speaker. "Cas? You still there?"

"Dean!" Cas exclaims, relief clear in his voice. "What happened? Did you-"

"What did you mean, Cas?" he interrupts, fingers tightening on the phone.

A brief pause, just the sound of breathing. "Mean by what?"

"By..." Dean squirms, "by booty call."

"Just what it sounded like," Cas says, and Dean totally doesn't picture him tilting his head to the side. "I sat on my phone and it somehow contacted you. I don't really understand it, considering the device is touchscreen, but-"

The phone clatters to the floor a second time as Dean snorts, wheezes for air, laughs so hard and loud and long he can't breathe. Sam snickers beside him.

"Knew it," he brags, beaming as he watches his brother pick up the phone again.

"Dean!" Cas scolds, his irritated tone only sending both hunters into another fit. "Why do you keep doing that? I'm glad that you're amused, but I'm going to hang up before this endless cycle continues."

"Wait!" Dean gasps, wiping a tear with his finger. "Cas, you don't understand - it's not a booty call. You butt-dialed me!"

"I fail to see the difference."

"Booty call equals an invitation to sex, you massive, uncultured dork."

Cas gasps, grumbling in that way he does when he's offended, "I am very cultured, Dean. I know every language there is-"

"Except slang."

"That is not a language!"

Laughter threatens to overtake Dean again as he quips, "Whatever helps you sleep at night, dude."

"You would help me sleep at night."

"What?"

"What?"

Sam facepalms.