She heard him singing as she moved her ear to the door. If he was showering, he was naked. She liked spying on her brothers when they were undressed. She licked her lips. She always watched them when they thought she wasn't looking. It was her favorite game, spying on her brothers when they were naked and sometimes even jerking off.
It had been awhile, maybe as long as a year, since she'd seen Billy's cock. She wondered if it had grown. Was it as big as Jimmy's? Had he grown more hair on his crotch and did his balls hang down heavily, like Jimmy's?
Her virgin cunt twitched and felt hot and heavy between her legs. On an impulse she pushed the bathroom door open slightly and peeked inside.
Billy chose that moment to shut off the shower and step out into her line of vision. He didn't see her as he reached for a towel.
She saw all of him, however. Her eyes widened as she gazed at his prick. It was as big as Jimmy's and he had indeed grown more hair on not only his crotch, but on his balls too.
The horny teenager held her breath. Both her brothers were turning into studs. How exciting!
Billy dried his crotch and hummed a tune as he examined his face in the mirror over the sink. She squinted to see into the room. He was looking for signs of a beard on his chin. She almost giggled.
But what drew her attention was his prick. It was long and thick and dark pink. She became so engrossed in his cock she failed to see him spy her in the hallway.
"I know you're out there," he said. "What the fuck do you think you're doing, Sis?"
When the door was pulled open, she fell forward, landing against the naked boy. She was too stunned to speak, but his cock stabbed her hip and they both sprang back.
He quickly wound the towel around his waist, hiding his prick from her probing eyes. "Hey, get out," he said.
But Penny became bolder and grabbed the towel, yanking it down. "I like to see it," she said.
"Jesus Sis, you're crazy," he said, trying to cover himself. "Do you know what you're doing?" He jerked the towel from her hand and tried unsuccessfully to tie it around his waist.
"Let me see," she giggled, grabbing the towel and pushing it behind her back. "You used to let me see your thing. Why can't I see it now?"
"Oh, Jesus!"
It was true that as children they had played doctor and nurse regularly. Now as Billy gazed at his younger sister he felt confused.
In a way he wanted her to look at his cock and admire him. On the other hand he knew it was wrong because his parents had instilled certain values in all their children.
Penny clutched the towel and openly stared at the naked boy. "Your cock got real big," she said, her eyes shining with admiration.
"Mom'll kill you if she finds out you're doing this," he said, suppressing a grin.
"Hey, it's lifting up," Penny said.
The boy felt a twitch in his balls. Damn it, he was getting turned on and by his own kid sister.
"Jesus, you better get out of here," he said.
The little brunette let the wet towel drop to the floor. When Billy didn't reach for it, she moved closer. "I like looking at your thing. It's sort of cute."
"Jesus, cute!" he groaned.
She moved closer, without thinking, reaching for his prick. "I don't mean cute," she said. "I mean horny and masculine."
"Hey, cut that out!" He moved back, hitting the wall. "Jesus, Sis, you can't do that."
"Just let me touch it a minute," she said.
"You're crazy," he said, but he stood still while she touched his cock.
He had noticed in recent years that his sister was growing into a very pretty young lady. She was built too. She had big tits like their mother and a nice round ass. He had wet dreams about her sometimes, but it had never occurred to him that she was horny too.
"It feels funny, but it's nice," she whispered, lightly running her fingers over his fuckpole.
As she spoke she stepped back and gazed down at the prize in her hand. The boy stared at her dumbly. He and Jimmy talked about cooze all the time, but they'd had little experience with sex. Now here was Penny, his own sister, squeezing his prick. His confusion increased. It felt good, but he knew he ought to make her stop.
"Are you a virgin?" he said.
"Yes, are you?"
"Hell, no." He lowered his eyes to avoid hers. He was a virgin, but he didn't want to admit it.
"Are you really not a virgin?" the young girl said.
"Shit, I've done it plenty," he said. Actually all he'd ever done was touch a girl's tits and french kiss. Once a girl let him touch her, down there, but only for a minute.
"Jesus, what about Jimmy?" he said.
"He's been around too," the boy croaked.
The way she was touching his cock was driving him crazy.
"It's getting even bigger," she said.
He was beginning to forget that Penny was his sister. He covered her hand with his. "Touch it here," he said.
She touched the tip of her fingers to the rim under his cockhead. "Here?" she said.
His cock rose up in her hand. "Yeah, that's okay."
"God, it's getting hard," she said, one hand cupping his balls and the other caressing his prick.
"Well, what did you expect?" he said. He was finding it difficult to breathe. Somewhere in his mind he knew he ought to stop her, but he was helpless. Her hands on his cock and balls felt too good.
"I watch you sometimes," she said, lightly stroking his prick.
"Yeah, when?"
"When you're getting out of the shower, like today, and sometimes when you're in your room."
"Well, I watch you sometimes too."
"Honest?" she grinned. "Did you ever see my pussy?"
"Yeah, once," he said.
"Did you notice all the hair I've got now?" His cock jerked in her hand. "Yeah, I noticed."
She pumped his prick until the skin pulled tautly over his hard-on. She breathed rapidly and felt the oozing moisture between her legs.
"Are you gonna come?" she said.
"Maybe," he gasped.
"Are you gonna come on my hand?"
"Yeah, if you let me."
"I'd rather you fucked me."
"Huh?" Sweat poured down his temples.
"Honest, I'd really rather you fucked me than come on my hand."
He groaned but didn't speak. He was filled with mixed emotions. He wanted to fuck her. God, how he wanted to fuck her. He was dying to lose his cherry and tired of jerking off. But she was his kid sister. If his folks found out they'd skin him alive.
"Please," the teenage girl whispered.
"Let me think a minute," he said, his cock jutting out from his crotch.
"You know you want to," she said.
"I gotta think."
His balls ached. God, they must be turning blue. He had to give her an answer soon or he'd dump his load on her hand.
Then Penny did something that took the decision out of his hands. She dropped to her knees on the bath mat, opened her lips and took the head of his prick into her mouth.
"Jesus, Sis!" he hissed. He used every ounce of control he could muster to control his orgasm.
She only held his cockhead in her mouth a moment, but it was long enough to convince him he had to fuck her.
"Okay, Sis, but you better stop or I'll come in your mouth."
Giggling, the teenage girl defiantly licked her tongue over his cockshaft. "You better not," she said.
But she was wise enough to know his orgasm was close. She gently cupped his balls with one hand and licked his cockhead. She tasted his pre-orgasm jism and shivered. Is this what jism tastes like? If so, she wanted him to come in her mouth.
Suddenly he pushed her head back and grimaced. He pulled her to her feet and backed her against the wall. "Sit up there on the sink and I'll fuck you," he said.
She was very turned on, but the thought of fucking here in the bathroom didn't appeal to her. "How can we fuck if I'm sitting on the sink?"