You fuck Bobbin.

You get on your knees and give a glance to Bibbi. She nods at you encouragingly.

"Her eggs are deep," she says, still squeezing her own breasts. "Your seminal fluid will help her lay them." You swallow, realising what you actually have to do you. It's quite an idea, and you know that it's actually impossible for a human to impregnate any animal on the farm. You physically cannot fertilize Bobbin's eggs. But she needs you to pump her full of cum anyway. You put your arms under her thighs and pull her towards you. Her hand finds your cock and she to guides you towards her hot opening and you bring her closer. The tip of your dick presses against her slick lips. You move your hands onto her hips for better grip and continue to push her down. Her slit parts, accepting your cock, her excessive wetness dribbling down your shaft. You groan as she takes you deeper and when she finally bottoms out on you an odd purring noise thrums from her chest. Her feathers tickle your crotch a little where you're joined and she wraps her arms around you.

Hugging you close she pulls your head down so you can feel how soft her breasts are on your face. Combined with the downy feathers on her chest it's like the most comforting, silky soft pillows you've ever felt. Your mouth instinctively opens and your tongue searches for her 'nipple'. Though you get a mouthful of feathers you find the stiff nubs and suck on them, eliciting gasps from Bobbin's beak. She's sensitive there, and you feel her pussy getting wetter from your attention.

You start to thrust now, wanting to give her as many sensations as possible. She moans, hands gripping onto the back of your head as you pick up the pace. She's getting hotter around your cock, and when she starts to join in and bounces on you it makes you grunt. The friction of her undulating cunt muscles is amazing and you think you know what's starting to happen. Bobbin can't help her utterances now, trying to suppress her noises but letting the odd cluck escape as you fuck her deeply. Her vocalisations continue to rise and it's turning everyone else's attention to you. The other chickens shift in their nests, playing with themselves if neither of your sisters were presently pleasuring them.

Noticing the atmosphere you realise you're on a few strokes away from finishing now.

"I'm gonna cum," you tell Bobbin, who continues bobbing wildly on your stiff cock.
"Yes please," she hisses into your ear. Her beak nibbles your ear lobe gently and it's almost like a trigger for you. Grunting as your erupt you pump harder. Your cum spurts forcefully into the chicken's twitching hole and she feels the hotness spread inside her. "Yes! Yes! Bwaka!!" Bobbin climaxes now and she shakes violently. You hold onto her with a firm grip, still emptying your balls into the girl, and she seems to convulse harder with each jet of cum you blast into her.

You feel hands on your wrist and you let your arms get pulled apart. You let go of Bobbin and she falls backwards, slipping from your cock which bounces back upright, covered in your cum and her lubrication. It was Bibbi who made you let go of her sister and she smiles at your erection. You both turn your attention to the chicken writhing on the floor, the orgasm still roiling through her and building as her internals shift. The egg is emerging from her lips, stretching it, your creampie getting pushed out as well and running down her ass cheek, turning her tail feather into a matted mess.

"Uhnnn! BWAAAWK!" she clucks hotly, releasing the egg from her pussy and into the hay. The sudden relief seems to give her another orgasm and she curls into a convulsing ball, feathers ruffling. You can't take your eyes off the sight of his birdgirl cumming over and over again. You grit your teeth as Bibbi strokes your cock, scraping the carnal mess from your shaft and licking it off her fingers.

"Well done," your big sister says, suddenly next to you.

"Wow," your other sister says, on the other side of you. You look from one girl to the other and notice how greasy their chins are. Some very satisfied chickens are gently stroking the eggs they just laid behind you.

"There's two more chickens left," Betty says, watching Bobbin twitch in the hay.

"I'll get one," volunteers Jenny, sucking some leftover flavour from her fingers.

That leaves you with the last one then, obviously.