A stranger, a stallion in his mid-20's by the looks of him, wandered into Sugarcube Corner one afternoon. His coat was grey and his hair was brown--an odd combination, but he pulled it off. He was an earth pony, and his cutie mark was a neat black grid. Pinkie immediately started mentally planning his "Welcome to Ponyville" party.

"Hello, there!" she called cheerily, waving. "What can I get you?"

He dropped three bits on the counter in a neat stack. "Chocolate milkshake. And a conversation, if you don't mind."

"Not at all! I'm always happy to get to know new ponies!" Before he could quite process what had happened, she had poured two milkshakes--chocolate for him, strawberry for her--and whisked both of them to a table near the window. "So, what's your name? I'm Pinkie Pie!"

"I've heard of you, Pinkie Pie. My name is Obsessive Compulsive, but most people just call me OC. I roam Equestria in a search for answers."

"About what?" she asked, taking a sip of the milkshake.

"Everything! I want to make it all fit. I want it to make sense. That's what my cutie mark means--a logical, orderly world where everything makes sense."

Pinkie shrugged. "I think things that don't make sense can be fun sometimes. Like Discord!"

"Discord might be chaotic, but he still makes sense in a way. He's chaotic, and he always will be. That means at least one thing is predictable--his chaos. But I'm not here to ask about Discord, I'm here to ask about you."

"What about me?"

He took a long sip of the milkshake before he replied. "Your 'Pinkie sense'--or, more specifically, what category it fits in?"

"I'm not sure that's a good idea. Twilight tried to categorize it once, and it didn't work very well."

"No, not like that." His hoof tapped the table, emphasizing his words as he spoke. "See, Cheese Sandwich, famed Party Pony, has a 'Cheesy Sense'. You're also a Party Pony, so it could be a Party Pony thing--but then your sister has it too, and she's the exact opposite of a Party Pony!"

Pinkie scoffed. "You clearly haven't seen her on Sugarcube Corner's Open Mike Nights!"

He waved a dismissive hoof. "The question I want to ask is, is it a family thing or a Party Pony thing?"

"Oh! I see. That's a waaaaay different question than Twilight had! This one won't get a piano dropped on your head. Probably."

OC nervously looked up at the ceiling, checking for pianos.

Pinkie giggled. "But your answer is--it's both! Not all Pies have the Sense, but a lot of us do. So do other families we're related to, like the Cakes and the Donuts."

OC did a double-take. "You're related to the Cakes?"

"Sure! Mr. Cake is Mom's brother! What, did you think they sent me to live with some random strangers?"

"Well... you never call them 'Aunt' or 'Uncle'..."

"When you were a foal, did you ever meet a guy who told you to call him by his first name even though foals are supposed to call grown-ups by their last names?"

"Well, sure, but..." Uncertain what objection he was going to raise, he instead drank some more of his shake.

"The Cakes are kinda like that, only not really, 'cause they like to be referred to by only their last names. But see, if they didn't, I'd be calling them Uncle Carrot and Aunt Cup. What kind of weird names are those? They're about baking, so of course they'd rather have their name be Cake!"

He tilted his head. "I guess that makes sense."

"It's the exact same reason my family doesn't usually go by Pie--we don't bake pie! And everyone in the more distant family branches go by the same principle. Like, Cheese Sandwich doesn't make sandwiches, so usually he goes by Cheese and-"

"Slow down!" He put his hooves in the air. "Go back! What was that about Cheese Sandwich?"

"Yeah, he's like a third cousin?" She laughed. "Glad he's not a first cousin! Really, anypony whose last name is a food with flour is-"

"Wait, what was that about how great it was he's not too closely related?"

"Now, as far as I can tell the Apples are far away enough that they don't have the Sense, probably because 'fourth cousin twice removed by a third cousin' makes no sense at all as far as I can tell..."

"Wait! Go back to Cheese Sandwich!"

"And it's far more common for Party Ponies in the family to have the Sense, but other ponies have it too sometimes. Come to think of it, I'm not sure if I've heard of a Party Pony who wasn't in our family."

"But what does Cheese- you know what? Never mind."

She smiled. "So, how long are you staying in Ponyville?"

"Just for the night. My only reason for coming was to talk to you about that whole thing."

"Then I'll have to hurry if I want to get your party ready tonight! Come back here at six o' clock, okay? I'll have it ready."

He looked up at the clock. "Pinkie, that only gives you three hours! How can you possibly do that so fast?"

"Eh, I've done it on a tighter schedule."

He shrugged. That was a road not even he was prepared to inquire down. He glanced down at his milkshake, but by now it was empty, so he stood up, thanked Pinkie, and headed for the door. As he reached it, Pinkie's tail began twitching furiously. Not noticing, he opened it and stepped out.

"OC! Wait!" Pinkie shouted.

A piano slid off Sugarcube corner's roof and landed on his head.

Pinkie sighed and turned away. "I tried to warn him..."

Author's Note

At this point I'm not sure if OC represents me, or the commenter who asked this question. Either way, this was fun to write, and he will return at times. Thanks for the question, VShuffler42!