"All right, come on in," she said tiredly. "You're probably going to if I say so or not."

Dave opened the door and entered her bedroom. He was only wearing a pair of jockey shorts, and the shape of his thick, soft cock was completely visible through the cotton. This was the first time Debby had seen her younger brother in his underwear since she'd started fucking. She couldn't help noticing that his dick was very well developed.

Dave grinned at her and sat on the edge of the bed.

"How you doing, Sis?" he asked cheerily: "What you doing up so late?"

"I'm thinking about the Cold War," Debby said sullenly. "What do you want to talk about?"

Dave grinned. "About your fucking Robbie and Steve."

Debby gasped. For several seconds she was too overwhelmed with shock to say a word.

"How did… oh my God, who told you that?" she stammered.

"Nobody told me," Dave admitted brazenly. "The other night I got suspicious and followed you out of the house." His grin broadened. "I watched the two of them taking turns with you under the highway all night!"

"You… you sonofabitch!" Debby cried furiously. "How dare you do something like that! I ought to…"

"Not so fast, big sister!" Dave said, happily but meaningfully. "Aren't you forgetting old Mom and Pop asleep downstairs? It wouldn't be so hard for me to run down and tell them about it."

Debby quickly fell silent. It was hard to believe that she was being blackmailed by her brother.

"Can't you imagine what they'd do if they found out you were putting out? Shit, I bet Dad would tar your ass but good!"

"What do you want?" Debby whispered meekly.

Dave licked his lips and smiled menacingly. He squirmed closer to her on the bed and rested his hand casually on her knee. For the first time Debby realized that his prick was swelling in his shorts, making an obscene tent as it stiffened to a full hard-on.