I was surprised to get a knock at the door at this time of the night. It was getting late, and I was about to lock up for the night. My mother-in-law, Kay, rushed in when I answered it, yelling, "Surprise," as she hurried off to the bathroom. I didn't know what to say, especially since her daughter had moved out only days earlier. I certainly didn't want to get into this tonight, so I took her bags to the guest room and let it be. When she came out of the bathroom and asked when Kim was, I lied and told her that she had gone with her girlfriends for a couple of days. I lied to her again, saying that I was heading to bed because I had a meeting in the morning.

Kay walked right past me naked as a jaybird the next morning as she headed to our bathroom. She must have thought that I had gone to work as usual or force of habit when she was here with Kim. I knew that Kay liked the shower in our room over the one in the guest room. Honestly, I don't know how she could have missed me, but her nose was buried in her phone, and she did.

I had always thought Kay to be a beautiful older woman. Sure, she was turning grey, but she wore it incredibly well. I had seen pictures of her when she was younger, and she definitely still had her figure. Nice long legs that led to her cleanly shaved pussy. Her perky ass had caught my eye on more than a few occasions, and let's not forget her store-bought titties. She'd bought those shortly after her divorce from Kim's dad. It was truly a shame that he never got to use them.

From my vantage point, I could see straight through to the shower. I should have given Kay her privacy but chose not to. I sat and watched as she fumbled with her phone and towel. Something fell to the floor when Kay unrolled her towel to hang on the hook. I didn't see what at first, but when she went to spit on its base, it came into view. It was a thick, eight-inch dildo that she suctions cupped to the glass shower surround at about waist height.

Kay adjusted the temp of the water before kneeling in front of the dildo. She stuck it into her mouth to coat it with spit before she turned, bending at the waist to line it up with her twat. She spread her labia with her finger as she leaned back into the phony phallus. She rocked back and forth, driving it into her pussy while rubbing her clit. Kay went weak in the knees when her first orgasm hit her.

I watched in awe as she pounded the toy into her twat, making a creamy white froth coat the sex toy. She leaned and let the toy slip from her slippery slit, only to guide it back into her anus. Kay grabbed a hold of the safety bar and proceeded to impale herself on the sex toy, crying out fuck my ass, David, fuck me, fuck my ass, Davy. "Holy crap, she was calling out my name," I thought to myself.

Kay had always flirted with me but never in my wildest imagination thought that she was serious. Yet, here she was, thumping her ass against the shower glass, driving a dildo into herself, calling out my name. Who wouldn't get hard after watching this?

I crept into the bathroom and knelt behind her on the other side of the glass, watching her finger her pussy while driving the dildo up her bum. I pulled out my cock and started to stroke my cock at a fevered pitch when all of a sudden, I heard Kay yell, "Don't you fucking dare jack off! Get in here and fuck me in the ass!"

I certainly didn't need to be told twice. I stripped off my sleep pants and joined Kay in the shower. She swung her backside toward me, allowing me to shove my cock deep into her ass. Kay kept a hold of the safety bar while I railed her sphincter from behind. "You didn't think I was going to let my son-in-law go without while my daughter runs around being a hussy butt!"

Being a hussy butt, zipped through my head. Where had she gotten that from? Kay had been a slut ever since her divorce, and it was only a matter of time before she got around to me. Now, with her daughter out of the picture, Kay could get what she apparently always wanted. They were both sluts in either case. "Are you my ass slut, Kay?" I growled. Yes, she said, thrusting her ass against me as I pounded her. "My naughty fucking ass slut!" I said, slapping her buttocks. She again moaned, Yes.

I wrapped my arms around her waist and started rubbing he clit as I continued to give her a pounding. Kay threw her head about chaotically as a series of orgasms bolted through her like lightning. Remembering that there was a dildo stuck to the glass, I handed it to her, saying, "Put this up your cunt, Kay."

Her anus tightened on my shaft as she inserted the dildo into her vagina. I asked her again if she wanted to be my ass slut. "Yes! Make me your ass slut," Kay she shouted as she began to cum. "Fuck my ass, Davy. I know my prissy little bitch of a daughter won't give it to you, so I will. Oh, my fucking, Gawd, you're making me cum. Fuck it! Fuck my fucking ass, David! Fuck! I've never cum this hard in my fucking life!" she cried out.

I kept hammering away at her asshole until I shouted, "I'm going to cum, too, Kay!"

Kay turned and dropped to her knees, "Cum on my face, Davy boy. Cum on my face," she whimpered as she grabbed my cock with both hands. She twisted her hands like she was wringing out a cloth as she stroked the length of my shaft, telling me over and over to cum on her face.

My first two spurts splashed onto her mouth and lips. The next two shot across her face, landing in her hair. Kay rubbed the tip over her face through the remaining squirts of spooge. She stuck the head of my cock into her mouth and swirled her tongue around my tip as she squeezed my balls and shaft. The water from the shower slashed down over us as she continued to stroke my meat, rinsing it off any residue of our anal interlude.

Nothing could have prepared me for what happened next. Kay stuck her hand between my legs and slipped a finger into my back door while she kept sucking the tip of my cock. To my dismay, my cock stayed rock hard as she probed my prostrate while continuing to suck me off. Between her talented tongue and her pokey pointer finger, she made quick work of it. I blasted another load of cum down her gullet.

I grabbed her head, thrusting my cock against the back of her throat as I blew my wad. Kay took it like a pro. Nary a gag, even when I pushed the tip of my cock past her uvula. I finished nutting with my dick down her throat. Her smiling eyes stared up at me as she told me that she knew about Kim's indiscretion and thought that she'd help me get some petty payback.