Tommy/Bart, because the world needs more of this. Sorry it's so short
Just because you can run fast doesn't mean you don't have motion sickness.
Bart was going to be the death of him. Tommy was absolutely sure of that. He was positive Bart was actively trying to kill him. "Come on, Tommy. You can't be scared of a little roller coaster!" Trying. To. Kill. Him.
"I'm not scared, and it's not little. I just don't see the point of strapping myself into a metal death machine for the sole purpose of going flying through a swirl of colors and puking at the end." He crossed his arms as Bart smiled. He started rocking back and forth, arms behind his back, giving him the puppy eyes. That may have worked if he hadn't opened his mouth.
"Scaredy cat, scaredy cat!" he sing-songed. "Tommy is a scaredy cat!" Tommy huffed and started walking away from the metal monster. Barts eyes widened "W-wait Tommy, I didn't mean it! Come back!" He ran and latched himself to Tommy's arm. "Please, Tommy? Please can we go on the roller coaster? I promise it won't be that bad, and I'll do you whatever you want when we get off I swear!" Tommy sighed.
"Fine, I'll go on it-"
"-but you have to do anything that I want."
"Only one thing." Tommy smirked.
"One thing's all I need. Let's get this over with."
In the end, Tommy did end up sacrificing his lunch to the porcelain god Amun-Raaaauhg. Bart couldn't seem to decide whether or not he was going to be sympathetic or an ass, switching between the two every few seconds, and it was really getting on Tommy's nerves. It wasn't his fault that flying in a corkscrew while the car turned the opposite way made him sick. It was Billy's for getting all of the non-motion-sick genes. So while he was praying to Amun he was devising Bart's punishment.
It was going to have to be public, embarrassing, not easily forgotten. Something that he would never do normally. But also something that he wouldn't get arrested for when this happened. Public sex was out, but there was something else he could force him to do. His stomach settled and he left the stall. He smiled. That would work.
That night, as they laid cuddled on the couch watching a movie, Bart apologized. "I really really didn't think you'd actually rolf. I just thought you didn't like roller coasters, which is insane by the way." Tommy just pulled him close.
"Yeah, well, I know you didn't mean to get me sick." Bart kissed him on the cheek. "But there's still the matter of what you're going to have to do."
"Okay, hit me with it."
"We're going to have a date day-"
"-and you're going to be in a dress."
"...Not awesome." Tommy smiled.
"And just what do you think that roller coaster was?" Bart sighed.
"Exactly. Think of it this way, unless you get food poisoning you won't be throwing up after my idea." Bart groaned.
"This is payback, isn't it?"
"Yes Bart. Yes it is." And it was going to be awesome.