I was home alone, supposedly catching up on a few jobs around the house, but not really in the mood to apply myself energetically to anything important.

To avoid completely wasting my time, I decided to stick some washing on. I was rummaging through the laundry basket when I came across one of J’s lacy white thongs.

I love the smell of her used panties, and holding them up to my nose, I breathed in her powerful scent, and immediately felt my cock stirring.

I put the thong in my pocket, stuck the laundry on and went upstairs to our bedroom. I stripped off and pulled on the thong, loving the way the lace and silk felt against my stiffening cock and how the thin strip of material at the back pressed against my asshole.

I slipped on one of J’s tops – a cotton one with pretty pink and purple polka dots on, and lay on the bed, enjoying the feeling of her underwear softly caressing my skin. I pulled out a porn mag from my stash, a copy of Voluptuous.

I really enjoy reading porn featuring bigger, curvy women, proudly showing off their ample figures and getting licked and fucked. The fat girl porn, plus J’s panties, were getting me pretty horny. I reached a hand into my panties and started stroking my cock, slowly at first, as I turned the pages of the mag. As I wanked, I pulled the panties harder into the crack of my arse, feeling the material taut against my bum.

Just before J walked in and caught me...

I was really getting into it, and I must have missed the sound of the door, because the next thing I knew, J was in the room standing by the bed and staring down at me, a strange look on her face.

“What the fuck are you doing?” she demanded – then before I could answer, she continued: “No – don’t say a thing. I can see perfectly well for myself the kind of sordid shit you get up to when I’m not here.”

I started to get up off the bed but she pushed me back down.

“No, stay there, carry on with what you’re doing. I’ll stay here and watch.”

I looked at her without moving. “Go on,” she ordered, “carry on looking at your mag and get your hand back in those knickers.”

I found this turn of events completely unnerving, but also something of a turn-on, so I did what I was told. It felt awkward at first, but the idea of J watching me while I stroked my cock and looked at porn while wearing her panties felt more and more of a turn on.

I could sense J behind me, but if I looked round, she snapped, “Don’t look at me. I’m going to watch you, and you’re going to do what you’re told.

I carried on, feeling deliciously powerless and completely at the power of this sensuous BBW. Then, I felt J’s hand slide down the back of my panties, between the thong and my bum, then two of her fingers parted my ass cheeks as she started smearing something cold and slippery around my arsehole.

I looked over my shoulder, and could hardly belive what I saw.

J had stripped off and was naked apart from a huge strap on cock which she was now smearing with the same lube she had put on my bum.

“I didn’t know you liked wearing my panties – but then you didn’t know I had this, did you?” she asked.

“What… what are you going to do?” I asked. I could feel my pulse pounding and my cock straining in my panties.

“I’m going to pull that soiled thong out of your crack and fuck you up the bum,” said J. “Now get on all fours and stick your arse up.”

My heart was racing as I got up on my hands and knees. I felt J ease the thong aside and then felt the head of the strap-on pushing against my tight ring. There was a sharp pain as the tip pushed in and I gasped. J waited and then when she sensed I was just relaxed enough, started to push further in, until the obscene monster cock was right up my arsehole.

I groaned and looked behind me at J as she started rolling her voluptuous hips backwards and forwards to drive her cock in and out of my arse. He heavy tits were jutting forward and her beautiful belly just hanging over the strap-on’s harness, jiggling provocatively with every thrust, as she clung to my hips to get better leverage.

I could see our reflection in the full length bedroom mirror, me face down on all fours in my lingerie with my cock straining against the panties, J with the strap-on fucking my bum, and I knew I wasn’t far off coming.

“Oh God, J, I love the feeling of you fucking my ass with your cock – but it’s going to make me cum in my panties,” I told her.

“You’d better not shoot your load in MY panties,”replied J, slapping my bum. “If you do, you’ll have to wear them for the rest of the day, like the dirty pervert that you are.”

As she said this, she began thrusting more deeply than ever, and the pain mixed with pleasure was too much for me. I cried out as I spurted hot sticky spunk into my silky panties.

“You dirty bastard,” sneered J. She pulled the strap-on out of my hole and worked it between the panties and my balls, smearing my cum over the head before sticking it back up me. “Now you’ve got spunk up your bum as well. And you’re going to have to keep those panties on til bedtime.”

She pulled back out, and eased the thong back into place against my stretched and abused asshole.

“I will wash them for you,” I promised.

“Don’t bother,” said J. “I wouldn’t want them back after that. Keep them safe til I want you put them on for me again…