"U-Uncle Scrooge, can we please make a pitstop? I really need to use the toilet, but, uh, it's occupied..."
Scrooge turned to look at his nephew, baffled. "A pitstop? We're in the middle of the bloody ocean! You'll have to hold it."
Huey whined, sulking back to his seat, and curling back up against his radio. He heard Dewey laugh under his breath. He gave a glare at his brother, who responded with a smug grin.
He rest his head on the arm of his seat, not too close to the speaker of the radio, and tried to zone out to the sea shanties he was enamoured with earlier. Huey couldn't doze off this time, however. His bladder ached and kept him awake. Regardless, he shut his eyes and tried to rest.
He yelped as he felt something touch his thigh, trailing up to his crotch. His younger brother shushed him, giving him a stern look that soon melted away. Dewey shimmied over to his brother, hushing him once again. 
"Dewey, what are you doing!" Huey scowled under his breath.
"Let it out, bro..." Dewey purred. "If you need to pee, then just go."
Huey whimpered. "The bathroom's occupied!"
Dewey laughed, getting out of his seat and kneeling down on the floor. He gave a cautious look around the submarine, making sure no one was watching, before opening his mouth and gesturing inside.
"I am NOT peeing in your mouth!" Huey grimaced, using a webbed foot to push Dewey away.
"And you'd rather hold it for the next ten hours?" Dewey grabbed the other's member. "If you pee yourself, everyone will see and laugh at you. If you let me take care of it for you, no one will know and you'll be fine!"
Huey whinced at his brother grabbing his shaft, trying to think about what was being proposed to him but struggling from the throbbing in both his member and his bladder. "Oh, fine!! Just d-do it-" He huffed as he released his bladder, spraying a golden stream onto his blue brother's face.
Dewey didn't expect Huey to release so fast, and opened his mouth wider to catch the rest of the stream. The pee tasted nothing like he expected, it was warm and almost tasteless. It didn't smell of much, which made sense, as Huey had the best diet and water intake out of the three ducklings. 
He gulped the urine greedily, making sure to act fast so his mouth didn't overflow with the liquid. As he gulped, he savoured Huey's expression, one of guilt but also relief as his bladder emptied.
The stream started to weaken and eventually stop, leaving only a few drips of urine on the tip of his member. "I'll dry that off-" Huey spoke but was cut off before he could finish by Dewey closing his beak over his member. The red duckling almost screamed at the suddeness of it. 
Dewey's tongue lashed over the other's member, cleaning every single drop of urine left. Once satisfied, he lifted up, giving a satisfied sigh.
"Dewey! What the hell!" Dewey laughed at his brother's reaction.
"But look, no one noticed! And you feel better, right?"
Huey growled. "I do, but..." He crossed his arms. "You didn't have to be so weird about it."
"You're just angry you've got a boner, aren't you?"
The older brother huffed.
"I mean, I could always help you out with your new problem..."
"NO!"