Dean grinned evilly as Sam stood up and headed to the bathroom at the back of the restaurant.

Now was the perfect time to put his plan into action. Carefully, extracted the baggie of crushed Ex-Lax pills from his jacket pocket and grabbed his brother's glass of water.

"Dean," John commented, "What are you doing?"

The eighteen-year old put on an innocent expression.

"What? It's harmless," he told their father, "I'm just getting Sam back for putting toothpaste in the Oreos."

John raised an eyebrow, "By putting drugs in his drink?"

Dean chuckled and stirred the water with his brother's spoon, "It's just a laxative."

John stared at his eldest son.

"Don't say anything, okay?" Dean whispered as he put Sam's drink back and took a bite of his hamburger, chuckling to himself.

Moments later, his fourteen-year old sibling returned from the restroom and sat down, grabbed his water and took a long drink from the straw.

Dean glanced at John from the corner of his eye but their father said nothing. His view on the prank wars was that, as long as they didn't maim each other, he wasn't about to get involved.

W

Half an hour later, the Winchesters were on the road again, with nothing interesting to watch while they roared down the highway in the Chevy. Dean entertained himself by singing loudly- and off-key- to some raunchy rock music while Sam tried to read in the backseat.

After about an hour Sam grew restless, putting his book down and frowning, seeming unable to find a comfortable position.

"You okay, Sammy?" Dean commented from the front seat, trying hard not to smile.

The younger boy nodded but Dean noticed he had beads of sweat on his brow.

The eighteen-year old turned around and continued to sing loudly.

Five minutes later, Sam had both arms wrapped around his midsection and was groaning in pain.

"What's wrong?" John asked.

"I don't feel good," Sam muttered.

John glanced at Dean.

"Can we stop?" the fourteen-year-old asked hopefully.

His father looked up, "There isn't a rest stop for miles yet. Can you hold on?"

Sam nodded, gritting his teeth.

Dean, smirking, stared straight ahead so his brother couldn't see.

Ten minutes later, Sam was lying on his side, knees drawn up to his chest. His face was pale and large beads of sweat stood out on his forehead and cheeks.

"Are you all right?" John asked, getting concerned.

Sam shook his head, "I'm having stomach cramps."

Again, John looked at Dean. This time, Sam saw.

"What is it, Dean?" Sam ground out as a viselike pain squeezed his insides.

"Nothing," his older answered quickly.

"Dean," John said warningly.

"I may have, uh, put a little something in your drink at the diner," Dean admitted.

"What?!" Sam exclaimed and sat up, "What did you do?"

"Relax," Dean waved a hand, "It's just a laxative."

Sam's face, already pasty, seemed to blanch even more.

"You jerk!" he growled, "This is because of the Oreos, isn't it?"

Dean, smiling nodded, "You should have known I'd get you back for that."

"It's your fault if I-" Sam began but abruptly stopped, his face turning green.

"Sammy?" Dean looked at his brother, suddenly concerned.

"Oh no," Sam groaned and bowed his head, "It's coming."

"Not in my car!" John exclaimed, and sped the Chevy up, as though that would get them to a rest station faster.

Dean howled with laughter, that is, until the unmistakable smell of diarrhea filled the car.

"Lower the windows!" John snapped as Sam groaned in the backseat.

"I hate you," Sam snarled at his brother as his stomach cramped again.

Dean, though, couldn't contain himself and burst out laughing at his brother's misfortune, despite the smell in the car.

John glared at his eldest son, looking about as happy as Sam.

"You're going to clean this car," he told Dean, "And help your brother once we stop."

W

True to his word, when they finally pulled into the parking lot of a rest station, John handed Sam's duffel to Dean as told him to take the younger boy into the bathroom.

Embarrassed, Sam hurried into one of the stalls while Dean passed him a clean pair of pants and boxers and handed him pieces of paper towel beneath the door. Sam refused to speak to his brother. Dean thought it was funny, but he didn't realize how terrible Sam felt. He just wanted to change into clothes that weren't full of liquid shit and go back to the car.

Once he had cleaned himself as much as he could, Sam stepped out of the stall. The boxers and pants he had been wearing were a lost cause and he shoved them into the garbage before washing his hands with scalding water.

Dean, carrying his duffel, left the restroom, telling Sam he'd meet him at the car.

I'll get you back, Dean; Sam thought mutinously, just you wait.

Climbing back into the Chevy, Sam accepted the large bottle of water John handed him that he had picked up while his sons were in the restroom.

"Where's mine?" Dean asked.

John glanced at his eldest son, "You're old enough that you don't need me to hold your hand. You could have got yourself a bottle of water before leaving the rest station."

Sam smiled; he knew his Dad was just saying that to teach Dean a lesson.

The eighteen-year old frowned as they pulled out of the parking lot of the rest station, though he refused to complain again.

Sam relished the chilled water in the bottle as his stomach cramps eased and he slowly felt better, dreaming up ways at getting his brother back for his prank.

Author's Note:

Just another little oneshot I had waiting to be written.

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