As my fingertips delve into the split between her cheeks, I feel her warm p***y juice oozing out around the plastic dildo. My fingers move up and down her crack with each thrust of her hips and each clench of her ass muscles, smearing her sauce all around the crinkly opening between her cheeks. Coating my middle finger with lubricating p***y juice, I start teasing her asshole.
Timing my action with my sister's thrusts, I wait until she's pulling back and unclenching her ass cheeks to push my finger into her. On the first attempt, I get the tip in before she thrusts forward, locking my finger in place with her tightly clenched cheeks.
"Oh f**k!" Susan yells, "Push it in farther, Nick." Each time she pulls back, a little more of my lubricated finger disappears into her ass. After three or
