All of her

Sliding her dress over her head and tossing it onto the ground, you grip your sister's ass and grind your cock into the front of her soaking panties. “I want you Cait, obviously. I don’t just want a one time birthday fuck though. I have some very specific things in mind for you.”

You take a half step back to admire the body on your hot, older, married sister. Her pert nipples are poking through the cups of her bra. Down past her flat toned stomach you can see the dark patch of a trimmed triangle bush through the spreading damp spot on her panties. “What things John?” She asks as she brings her hands up to rub them on your chest over the light t-shirt you’re wearing.

You bring your hands behind Caitlin’s back and unhook her bra. Sliding the straps off her shoulders she lowers her arms so the item can slide off her body and onto the ground at your feet. She brings her hands back up under your shirt to caress your chest directly while you look openly at her bare tits. Large cups of pale skin with dark areola surrounding a tall erect nipple. They are positively begging to be touched, and so you do. Cupping each breast and running your hands over her nipples enjoying the hard feel of them as your palms drag over each one. “First I’m going to strip you naked Caitlin. Right here in the park you are going to show me every inch of that hot sexy body of yours. You’re going to show me each and every one of your secret treasures, at this table under this summer sun.”

“Sounds wonderful, what then?” Caitlin asks as she pulls your t-shirt off over your head and drops it onto the growing pile of clothes on the grass next to the picnic table.

You reach your hands back down to her ass, and lean over to put your sister's left nipple into your mouth. After sucking both nipples to diamond hard points, and hearing Caitlin moan and pant for your efforts, you straighten up and move your hands around to hook the waistband of her panties. “Then, sweet sister, I’m going to claim every one of your holes with a load of my cum.” You slowly pull her panties down to her ankles, going to your knees as you do. This leaves you at eye level with Caitlin’s curly, soft patch of pubic hair. You rub your hand through it feeling the hairs part around your fingers as you smell the musk of her arousal. You inhale deeply as you stand back up and move her hands to hook the waistband of your shorts. “As your birthday present to me Cait, I think you should cuckold your ass of a husband and become my dedicated cumslut.”

Caitlin lowers herself to her knees dragging your shorts and boxers with her. “So, cumming in one of my holes marks it only for your personal use?” Your cock comes free into the open air as she brings your shorts down to your ankles.

“Yes, and I plan to fill all three of them right here at this table before we go home.” You step up so your cock is right in your married sister's face. “Let’s start with that sexy mouth of yours.” Taking your cock in hand, you rub the head over Caitlin’s lips. Her hand comes up to take hold of your dick, and she sticks out her tongue to lick over the head.

“Mmm,” she groans as she swallows the pre-cum off the head of your dick. “Little brother going to use his big cock to claim my mouth?” She uses her tongue to lick all over your dick from the base to the head.

You gently grip both sides of her head, running your fingers through the soft silk of her hair. You push her head onto your cock, and she opens her mouth to take you inside. As the head of your cock goes past her lips Caitlin swipes all around it with her tongue. “God sis, your mouth feels so good. Just suck that cock, out here in the park, like a good slut.” You push her head further down, and she slides further down your cock. Once you push her down to the base, you let up on the pressure, letting your sister move her head on her own. As she backs off to the head of your dick, she brings her left hand up to grip the base of your cock. Seeing you eyeing the hand twists it until you can see the gold band on her finger.

“Like seeing my wedding ring while I suck your cock John?” Your sister pulls off long enough to ask before she plunges down your cock again.

“Fuck yeah Cait. Cucking Tom is a big turn on.” Your sister starts bobbing her head up and down on your cock. Down until her lips smash into her hand wrapped around your dick, and then back up until just the head is trapped inside her mouth. Back and forth her head moves, your sister sucks, and the pressure builds and builds in your balls. “Slow down sis, let me build up a nice big load for you to swallow.”

“Ummm,” she hums on your cock while pulling off. Once her lips clear your cock head, she moves her left hand to cradle your balls, and starts licking your shaft. She licks up the underside of your cock up to the head, and then put it in her mouth and takes you all the way to the base. You feel the head get pushed into your sister's throat, and she holds it there for a few seconds before sliding her lips back up to the head of your cock. While softly massaging your sac, she swipes her tongue around your sensitive tip. Then she drops back to the base again.

“Damn sis, you are one great cocksucker.” You take one of your hands out of Caitlin’s hair and gently rub her cheek. “Just take your time, and you’ll suck that load of cum out of my balls.” Caitlin raises her eyes to look at you as she sets a moderate pace sliding her mouth up and down your cock. It only takes a few minutes before she starts speeding up on her own with no input from you. “Wow Cait, just that eager for a big load of little brother’s cum huh?”

She pulls her lips of the head of your cock, and takes hold of it with her free hand. “Mmm, can’t wait bro. You gonna take these lips from Tom and claim them for yourself?” Caitlin aims your cock back to her face, and puts it back into her mouth.

“Yeah Cait. That sweet mouth is gonna be mine.” You take hold of your sister's hair, and start pumping your cock into her mouth. “Take that cock and suck out all my cum. Swallow my seed, and give me that hole. I can already tell you love the flavor of my cock. I bet you’ll love the taste of my cum too. You’re such a sl …” You’re attention is diverted to the path leading down to the picnic tables. “Oh hello, good afternoon.”