With one hand forcing Shawna's head down into the duvet and the other gripping her ass, Dylan emptied his bladder into his sister's bowels. When he was finished, he eased his cock out slowly, warning her, "You let one drop escape, and the next piss I take will go straight down your throat."
She did leak a little, but Dylan chose to ignore the tiny dribble that escaped before her asshole could close. He held her cheeks apart just enough to see her anus, and waited, knowing what would come. He had helped administer enemas to his sister before her shoots plenty of times, but never like this. After a minute, she began to moan. "Dylan, let me go to the bathroom."
"No," he said quietly, "not yet. You can take it." He released her asscheeks and stood up, circling the bed until he stood in front of her. She was still face-down on the bed. A fine sheen of sweat had broken out on her forehead. "Get on your knees."
"I can't," she whined. "I'll shit myself."
"I suggest you don't," Dylan warned. "Get on your hands and knees."
Clumsily, Shawna obeyed. Her enormous tits hung down between her arms, full and round. As Dylan forced his flaccid cock into his sister's mouth, he stared at them, thinking about Daisy's milk-filled jugs. He was worried about her being pregnant, in truth, but he was also a little excited. He hadn't lied to her about the changes he was anticipating in her body, and how he might use her. The thought, along with his sister's warm, wet mouth, began to get him hard again. He grabbed Shawna's head and began to force his stiffening cock down her throat. She took it without batting an eye. Only after four or five thrusts deep into her throat did she pull back, coughing. "I'm seriously gonna shit myself," she whined again. "It's so fucking bad, Dylan. Please let me go."
It had been several minutes, Dylan reckoned. He got off the bed, his hard dick bobbing in front of him. Peering between her ass cheeks as she knelt quivering on the bed, he observed with satisfaction the way her anus spasmed and distended. He found that he liked knowing she was doing everything she could to keep his piss inside her. Reaching out, he ran his finger down the crack of her cameltoe. She was sloppy wet.
"Get up," he ordered, and Shawna scrambled awkwardly to her feet. Without permission, she waddled towards the bathroom door.
"Not in the toilet," Dylan demanded before she could lift the lid. "Get the bucket from under the sink."
Shawna was red-faced and panicky. She scrambled for the bucket and, without being told, squatted over it. Dylan stood behind her, smirking. "Squirt my piss out of that nasty fucking asshole."
His sister let out something that sounded like half a scream and half a moan as her anus dilated wide, releasing a torrent of yellow liquid into the waiting bucket. Her own piss mixed with his as she released everything at once, gasping and howling. Small bits of waste escaped from her gaping hole, but Dylan ignored it. His sister did this so often she kept herself rather clean, and most of what came out of her was his own piss. He found this degrading activity strangely erotic, and as she shivered and shook over the bucket, waiting for the rest of the enema to work its way out of her, he stroked his cock slowly.
What seemed to be the last few squirts of piss finally escaped from her spasming anus, and Dylan ordered her to dump the contents of the bucket into the toilet. Then Shawna was to get into the hot tub and wash herself. She obeyed, her eyes watery from the enema, her face still red with shame. Once she had climbed into the hot water, Dylan stood beside the tub and ordered her to wash his cock. She did, her tiny hands stroking his shaft until they had built up a lather. She used the spray nozzle to rinse him clean. The sensation was pleasurable, but Dylan knew it did more for her than it did for him. They had discovered that together one night when his parents were out to dinner. Naked and half drunk, he and his sister had sat in the hot tub, he in the water and she on the outer ledge with her legs spread, directing the spray onto her clit and even her nipples. He had talked dirty to her while she did this until she had cum, moaning his name.
Dylan ordered her to do it again. Looking somewhat sheepish, Shawna got out of the water and sat on the ledge, spreading her legs for him. She adjusted the nozzle to the more intense, pulsating setting and directed the spray at her own pussy. Still stroking his cock, Dylan watched as his sister pleasured herself. She was very good at faking it, especially since she had gotten into porn, but he knew when she was truly enjoying herself. He watched her lips swell ever so slightly and her nipples stiffen. He wanted to suck on them, but he restrained himself, forcing himself to watch as his sister came closer and closer to orgasm.