Sarah agrees, and Doug's horizons expand

"H-how do I get bigger?"

"Just to be clear, you'll let us fuck your brother if we tell you?"

"Yes."

Jessica, the girl with the 3-foot dick, grabs Doug's leash away from your sister and starts explaining. "What you have to do is take a boy, like this one here," she tugs on the leash for emphasis, "and keep him full up with cum for a week or so. Then you suck his boycum."

Sarah gives Jessica a doubtful look.

Another girl, Anna, pipes up, "No, it's true! My big sister says there's something in girls' cum that makes cocks grow, but since boys can't grow real cocks, it just builds up in their little balls."

Jessica starts talking again as she lines up her three-footer to Doug's asshole, "So we're doing you a favor by starting him off for you."

"No need to thank us," Anna added, as she **** her smaller two-footer into Doug's mouth.

As Jessica and Anna started thrusting in unison, violating both of Doug's ends at once, Jessica added, "Of course, we need to get some plugs and a chastity cage, so we don't waste anything.

After Jessica and Anna finish, Doug finds himself fuller than he's ever been before, but rather than finding relief after they pull out, he finds himself invaded again by another pair of cocks. The process repeats again and again until Doug is on the final two girls. Just as they are almost done, Jessica comes back from a trip to the supply cabinet, with a ballgag, a buttplug, and a selection of chastity cages. As the two girls finish and pull out, Doug's holes are plugged up.

Jessica then holds up a few of the cages to his crotch for comparison and selects the smallest one. "Looks like your brother here takes the extra small." Locking it shut, she adds, "Hmm... a little loose, but I think it'll be fine."

Anna pipes up, "That's good, Sarah. My sister says the smallest boys work the best."

Finally free of the girls, Doug tries to move, but finds the best he can do is wobble back and forth. His cum-filled belly is so bloated that he can't even crawl, and the weight is far too much for him to stand up.