Combination of >>933630 and >>281475
 
I came across this fanfic, only available as a textfile and thought it suited these two pics
 
Yellow rain
 
Rainbow Dash hurtles through the air as she explores ahead of her friends. She wasn’t out scouting for signs of foul play or danger, oh no. Her bladder was filled to burst and she needed to pee, badly. She glides through the sky with haste; her dark pink peepers scan the area below thoroughly. “Come on, come on” she says anxiously, Dash soars over a small path parallel to an open field; it separated by a low wooden fence.
 
As the urge to go mounts she screeches to a halt, she hovers in the air and gazes over the land. To her dismay there are no toilets in sight, Rainbow sighs as she descends to the ground. Her hooves clack on the stone pathway lightly; she retracts her wings as she stands trembling. Rainbow Dash crosses her hind legs as they quiver slightly, Dash throws her head back and looks around the area.
 
Rainbow spies at a meagre bush at the wayside, “Nah…I can’t, what if one of the ponies sees me?” she thinks to herself. Then she glances at a nearby apple tree, Dash shakes the thought from her conscience vigorously. Then, an epiphany strikes the pegasi like a sack of apples. Rainbow stares up at the sky; her attention becomes fixated upon a large cloud floating above the pathway.
 
With no other options around Rainbow zooms up to the ball of fluff without a second thought, beads of sweat form on her brow. “Oh my gosh, oh my gosh, oh my gosh” she complains as she squats down sharply. As Dash lowers her flank she balances herself with her forelegs; she raises her vibrant and brightly coloured tail aloft. Rainbow Dash exhales deeply, freshly brewed piss courses out from her bladder and squirts out of her urethra quickly.
 
A broad stream of misty yellow fluid pours out through her vulva like a raging waterfall. Rainbow Dash lets out a hearty sigh of relief “Aaaaaaaah!” as she empties her bladder, the golden fluid passes out of her system and is rapidly absorbed by the spongy texture of the cloud. “Ugh…Ugh, ooooooooooh” Dash moans as she throws her head back, her mane flings backwards and cascades down her shoulders.
 
The rest of the gang start to catch up to the urinating Rainbow Dash as they parade up the road. As Dash’s flow begins to lighten up she breathes out contently, “Aaaaaaaaah, much better” she says calmly. The other ponies near Rainbow’s bathroom in the sky, the band of mares stroll along as Rarity enquires “Darlings, did any pony see where Rainbow Dash went off to?” to her friends.
 
“Um…I-I think I saw her fly over here…” Fluttershy answers meekly, Twilight leads the group from the front alone as they search for Rainbow Dash. “Don’t worry girls, we’ll get Rainbow and then we’ll go see princess Celestia” Twilight says as she walks under Rainbow’s newest toilet. As she lifts her hoof to take another step a blanket of yellow water washes over her suddenly.
 
Twilight freezes with her hoof in mid strut, her coat, tail and mane are all drenched in Dash’s warm piss. Her mane falls down her face and over her eyes as Twi slams her front hoof on the stone cobbled road. “Are you okay Twilight?” asks Fluttershy as the girls look on in silence.
 
Rainbow Dash jumps up and down on the cloud to clear her excretion from its contents. Furious, Twilight flicks her urine soaked mane from her face, droplets of pee fly out in all directions. Suddenly, a familiar voice bellows from below Dash as she stops hopping on the cloud, “Hey who’s up there!?” Twilight demands. Rainbow timidly pokes her head around the edge of the cloud, “Rainbow Dash!?” Twilight says in surprise.
 
“What was that for?” Twi asks bemused, as Rainbow scrambles for an answer a peculiar scent engulfs the area. All the other ponies start to sniff at the air; they look at each other with puzzled expressions. Pinkie Pie sniffs at the air; she follows the pungent smell like a dog traces a scent. “Ugh…I-It was a prank, ha” Rainbow says hesitantly, Pinkie Pie slides past her friends as she sniffs the paving intently.
 
She walks up to Twilight’s side slowly, Twilight gazes up at Rainbow Dash”A prank?” she asks perplexed. “Pretty funny huh?” Dash asks unsure. Pinkie Pie takes a big whiff from Twilight’s urine soaked mane. “Eeeeewwwww…Twilight you smell funny…” Pinkie Pie announces as she reels backwards, the unicorn lifts her hoof to her snout and breathes in her new essence. Her nose shrivels up in disgust as she recoils her head immediately.
 
“Eugh! Rainbow what did you dump on me?” she asks vexed, “Cider…” Rainbow replies shortly as her eyes dart from side to side. “That’s not cider” Pinkie Pie pitches in, all the ponies direct their gaze to Rainbow Dash. “It is…Or was…A while ago…” Rainbow admits, Twilight’s eyes widen in shock as the penny drops. The other ponies cringe as Twi begins to fume with anger, Rarity, Pinkie and Fluttershy take a step back as Twilight gears up for a meltdown.
 
Applejack brushes past the others as she walks to her friend’s side, “I-It was an accident I swear! I needed to pee and…I couldn’t find a bathroom and-and.” Rainbow says getting flustered. “Now don’t go blowin’ a gasket, Twi, Rainbow didn’t do anything on purpose. Did ya, Rainbow?” Applejack asks calmly, Rainbow shakes her head with a frown enveloping her features. Twilight glares up at Dash with ire as piss drips from her mane, “Come on, Twi” AJ pleads.
 
Twilight closes her eyes and inhales deeply, gradually she breathes out again. Her breath sends specs of Rainbow’s pee spurting off of her snout, slowly she opens her eyes. “Eeeeeeeeeeeeeeeewwwwwwwwwwwwwwwww!” Twilight cries out, “Now come along ya’ll, we’ll get Twi nice an clean in no time. Especially if we all pitch in” Applejack says as she looks up at Rainbow Dash.
 
Rainbow meets her gaze and rolls her eyes, “All right” she concedes. She jumps down off the cloud as the other ponies form a path for Twilight. The gang then escorts the stinking mare back into town for a much needed bath. Later that night Twiley sits annoyed in a large tub with her forelegs crossed, she pouts as her friends do their part.
 
Rarity lovingly caresses her mane with a strong shampoo; Applejack and Fluttershy work her back with soft pink sponges. A collection of soap suds gather on top of the water’s surface as Pinkie Pie and Rainbow Dash polish her back hooves vigorously, her legs stick out from the water and the suds. Rainbow starts to smirk as she says “You gotta admit it was kinda funny” to her friend, “No it wasn’t, Rainbow” Twilight snaps petulantly. Her friends start to giggle lightly at their little dialogue. The ponies work on through the night to get Twilight to…Not reek of piss…As much.