Coccyx
The main bridge crew and the other chiefs are all off shift and in the rec room, absorbing the precious downtime between the catastrophes that seem to follow them around. Dr. McCoy is drinking with Chekov and Scotty, both of whom could drink him under a table without even trying. This time it's not a contest, thankfully, just unwinding after a long, tedious day. McCoy's content to listen to Scotty lecture the kid on... some engine nonsense he honestly couldn't care less about, and enjoy the whiskey from Scotty's stores.
An engineer - female - crosses the room and comes up behind Chekov, crossing her arms around his shoulders, bosom pressed against the back of his head. "Hey, sweetheart." McCoy's eyebrows raise.
Chekov looks up to her face and smiles. "Oh, hello, Maria! How are you?"
"Tired." She slumps down to rest her chin on his head. "Thinking about turning in early. You?"
Scotty snorts into his whiskey, coughing away the burn. Chekov blinks over at him. "Are you alright, Mr. Scotty, sir?"
"Fine, fine." He waves him off, biting against a laugh. Maria glares at him over Chekov's head.
"Anyway, Pasha, I was wondering if you were going to bed early like me?"
Chekov shakes his head with a smile. "Mr. Scotty was telling me about very interesting things, actually, and I am very not tired!" At this he pulls out of her grasp and turns to regard her seriously. "But if you are tired you must rest. We cannot have you sleeping on the job!" He smiles brightly at her, and she sighs and shakes her head.
"You're too cute." She ruffles his hair and walks away, out into the corridor.
As soon as the door closes Scotty bursts into hysterics, McCoy chuckling. Chekov just looked confused.
"What? Why are we laughing?" McCoy rubs at his face, then pats Chekov's shoulder.
"Oh, bless your naive little heart." Chekov cocked his head to the side.
"I am sorry, but I am not familiar with that?" Scotty just laughs harder - he's red-faced and barely breathing at this point. Maybe he's drunker than McCoy thought.
McCoy drains his whiskey. "It's a Southern thing, kid. Hard to explain unless you understand."