Word Count: 1100+
Warnings: Very mild language
A/N: My tribute to April Fool's Day.

Sure, Sammy said it was an accident.

Dean didn't buy it. It'd been a long, sweaty, bloody, and mud-filled hunt. Dean had been through all but one of his shirts and, after finally making back for a shower, he came out to find Sam had used - not either of his grungy shirts, oh no - he'd used Dean's last clean shirt to mop up some spilled oil.

That left Dean with two choices. First, which shirt to wear: either of the nasty, blood-and-grime covered ones or the oil-soaked one? (He went with the oil. He could go into a Biggerson's with oil on him. Not so much with gore.) Next, how should he get Sammy back?

Feeling nostalgic, he went with a classic.

Compared to some of his other pranks, the towel one was simple, childish even. Chalk it up to giving his little bro the benefit of doubt. Just a little.

Returning to the bunker after yet another messy hunt (was there any other kind?), Sam hit the shower. Couldn't blame the guy, really. Dean took that opportunity to sneak into the bathroom and nab some stuff.

One of the perks of living in a Men of Letters bunker was all the little hidey holes everywhere, perfect for stashing all their clean towels and Sam's bathrobe.

A handful of minutes later, he was rewarded with Sam, dripping wet and clutching a dirty shirt over his privates, glaring at him. "Dude, what the hell?"

"What, Sammy? At least I didn't soak them in oil."

"I told you, that was an accident."

"Of course it was. So was this."

Sam nodded. "Okay, okay. That's how it's going to be. Just remember, you started it."

"Uh, no I didn't."

And so it began.

On Tuesday, Dean discovered itching powder on his kleenex. Unfortunately, he found that after he used it.

Wednesday, a open can of sardines mysteriously found their way into Sam's room. Hours passed before he returned and found them.

For two days, things stayed calm, business as usual for the brothers. After a late night, Dean collapsed into bed. An hour later, the 1812 Overture blared from his phone, full volume. Cursing, he fell off the bed and landed hard on the concrete floor.

Revenge came on Sunday. While brewing a fresh pot of coffee, Dean heard a loud crack reverberate throughout the compound, followed closely by Sam's surprised shout. Smirking, he continued his task. A few moments later, Sam burst into the kitchen.

"What the hell, dude? A firecracker, in the library? There's, I don't know how many, priceless tomes in there, and you rig it with a firecracker? Are you five?"

"It was under the table, away from the books. You only wish you could rig traps that good. And you started it."

Sam threw him that look, tossed his hands up and stormed out.

Dean didn't know where Sammy found the smoke bomb. But when he opened his door into his room on Monday, there it was. Underground bunker? Smoke? It took the rest of the day to clear. But, he had to admit, Sam did indeed know how to set a trap.

That night, Dean ramped it up a notch. Always a fan of the classics, be it music or pranks, he grabbed some saran wrap and headed to the bathroom after Sammy went to bed. He applied one layer over the top of the bowl, under the seat. His brother's litany of curses the next morning was the best alarm he'd ever woken up to.

Okay, the toilet was bad. If pressured, Dean might have admitted that. But nothing excused what Sam did next.

It was one thing to mess with a guy - the brothers did that all the time - but it was another to mess with his food. It was an unwritten rule.

You don't screw with a guy's pie.

Wednesday had been good. Relaxing even. Dinner came and Dean dove straight to his main course: apple pie, topped with piles of whipped cream and three cherries. The first bite, he devoured, too fast to taste. The second, his jaws slowed, tongue pausing midway between switching the pie from one side to the other. Choking, he spat it out. Salt. Overpowering all else, salt. What he took for sugar crystals sprinkled across the crust was, in fact, salt.

And it was in the pie too. No matter how much Dean scraped off, the flavor stayed. Stubbornly, he even tried just the filling. No good.

Fine. If that's how Sam wanted it, alright then. It was war.

Thursday, his brother took the Impala out on an errand. Perfect. It took a bit of effort but, thirty minutes or so later, he had his crown jewel prank set and ready, just waiting for his brother to open the door.

Dean sat in the library, fingers drumming on the table. He sighed and checked the clock. With a groan, he dropped his head backward, letting it dangle. What the hell was taking so long?

The faint rumble of an engine answered him.

Biting back a snicker, Dean leapt to his feet. He strained his ears, wanting to hear everything that happened next. Grin taking his face, he listened to the muffled engine pull into the garage above and… and… that wasn't the distinct purr of Baby. No, that was the poorly-tuned rattle of Cas' truck.

Crap.

Dean rushed the stairs. Above, the engine cut out. He took them two at a time. C'mon, c'mon, faster! He could make it, just a bit more… The door to the garage creaked open.

A resonant splash echoed through the bunker, followed by a rush of water flooding down the stairs. A 55-gallon trash can - so recently filled with water, currently empty - rolled into view.

Dean stopped. Silence, broken by irregular dripping, surrounded him. He ran his hand over his face.

"Um, Cas?"

"Dean," came the reply from above.

"You okay?"

"I'm wet." Pause. "Is this holy water? Some kind of new demon trap?"

"Not so much." Dean scratched his chin. "Uh."

"Dean, why was there a trash can full of water propped against the door?"

"Oh, that was for Sam. Long story."

Footsteps rang against the wet stairs. Castiel came into view, pants, shoes and lower half of his overcoat soaked through. He eyed Dean. "You and your brother are engaged in some form of prank war. Again."

"Apparently not that long."

"I'm going to dry off." The angel rolled his eyes and moved past Dean.

"Sure thing, buddy."

Dean followed him downstairs, sitting back down in the library while Castiel wandered off. He scratched the back of his neck. Sighing, he shook his head. Not the best prank execution. A shout from Castiel interrupted him.

"Where are all the towels?!"