I guess, if I’m being totally honest, it was my fault that it all started. And, come to that, my fault at the direction it took, as well. I’d been a bit late down for breakfast one morning and had just grabbed a piece of toast. I was standing behind my big sister, Izzy, eating it, while she, Mom, and Dad were finishing theirs. Izzy got out her compact, to fix her face or whatever, as she seemed to do like about a gazillion times a day, and I nibbled my toast into a circle and held it up to my face, making fun of her. Dad started laughing, and Mom spluttered as she tried hard not to.

Izzy turned around to see what was going on and caught me. “At least my face isn’t beyond hope like yours, Logan,” she said snidely. Adding, “you ugly little troll,” before flouncing off.

“Harsh,” I said to my folks. Dad shrugged noncommittally, and Mom gave me a ‘what did you expect’ look;I decided there and then that I’d have to get her back. As I left the kitchen and saw that she’d left her handbag on the hall table, I hatched a cunning plan.

I went upstairs and rifled through the washing basket. I was somewhat of an aficionado of my sister’s dirty panties by this stage, and I was looking for a pair of grade ones. Number threes, the top grade, I reserved for stashing away for a late-night jerkoff session. The appearance of those in the basket normally followed one of her nights out. I wasn’t a hundred percent sure, but I figured she was doing it, even though she didn’t seem to stick with any one boyfriend for all that long, and the smell of number threes was to die for. But I wasn’t a complete monster, so I went with a pair of ones.

I guess that this might be an appropriate time to confess that I’d had an inappropriate thought or ten about my big (by one year) sister. It was hardly my fault: I was a very horny sixteen-year-old, and she was very cute, with dark blonde hair, styled with what she called ‘curtain bangs’ framing her lovely face, deep blue eyes, and a little button nose. Oh, and she had boobs and an ass that made me want to dribble. If I ever forgot how sexy she was, my buddies were always only too happy to remind me. But she was my sister, so my desires and fantasies stayed firmly in my bedroom. Mostly.

Checking that Izzy was still in the bathroom, I went back downstairs and opened her bag. It was the work of a few moments to catch the label of the panties in the hinge of the compact, and then arrange it so that they were hidden below all the other crap in there, and the compact was near the top.

Depending on what her schedule was, sometimes Mom gave us a lift to school, and that was one of those days. All the way there, every time Izzy seemed to be going for her bag, I looked at her with a knowing smile. That earned me several frosty glares, but it meant that by the time we were dropped off, Izzy was desperate to check her face. I followed her all the way inside until she met a gaggle of her girl friends, and then continued on around the next corner.

Spinning back and peering, spy-like, back at them, I couldn’t help smirking as her hand delved into her capacious handbag. The looks on her friends’ faces as a pair of pink panties appeared out of her bag were absolutely priceless.

Her face went bright red and she was visibly spluttering as she tried to persuade them that she didn’t know how they got there, and she was in fact wearing a pair; their laughter and pointing fingers suggested that they weren’t entirely convinced.

I was still wetting myself laughing as her head spun around and she spotted me. I didn’t have to be an expert lip-reader to see her mouthing, ‘You are so fucking dead’ at me, and I ran off to tell my buddies all about it.

I knew that she’d try to get me back, but I didn’t know when or how, so the next few days were a bit tense as I waited for the hammer to fall.

When it did, I had to nod my approval: nicely played there, sis! There, in my underwear drawer, was nothing but a single pair of what were unmistakably Izzy’s tiny bikini panties. And it was, of course, soccer that afternoon. Without much hope, I checked in the washing basket, but, much as I hated to admit it, she wasn’t that dumb. So, I had two choices: risk getting caught with girl’s panties on, or go commando. The idea of running around for a couple of hours with my dick bouncing around, chafing in my shorts, wasn’t very attractive, but neither would be the reaction if I were caught wearing her skimpy undies.

My guess is that Izzy tipped Rich Morgan off, because he just happened to barge into me as I was getting changed, leaving me lying on the floor with my butt hanging out and my cock and balls barely covered.

They were, quite understandably, fucking ruthless. For days!

Two days later, I stood in front of Izzy’s panty drawer, wondering how I could tell which she’d wear next. “Oh, well,” I thought, as I rubbed the itching powder I’d bought from Amazon into the gusset of each pair, sniggering to myself as I did.

I watched her like a hawk over breakfast, and while Mom drove us to school, but as far as I could tell, she was behaving perfectly normally. Disappointed, I even checked the Amazon app on my phone, but it didn’t give any idea how long it took to take effect.

In the cafeteria, I saw her sitting with her friends and, when she spotted me, she gave me an absolutely filthy look. Yes! Result! I cried silently, while outwardly trying to look the picture of puzzlement and innocence.

When I got out of school, Izzy was sitting on the wall outside, waiting for me. “I suppose you think that was funny, don’t you?” she said bitterly. She was sitting kind of oddly, with her hands pushing her skirt down between her thighs. Then my cock stirred as the truth dawned on me.

“You’ve taken them off, haven’t you?”

She turned and looked daggers at me. “I didn’t have much fucking choice, now did I, Logan? I was scratching myself like a nympho on heat ... you bastard!”

“Sweet!” I said, laughing. “So you had no panties on all day?” Her evil glare might have given lesser souls pause for thought, but my hardening dick and my immense amusement left me impervious as I carried on giggling.

“I will so get you for this...” she hissed.

Once again, I was paranoid as fuck all the next day, waiting for her to take her revenge, but she was being suspiciously nice to me.

By the time we were walking home after school, I was starting to wonder if she was thinking it had all gone a bit too far.

“You know, I can’t stop thinking about you wearing my panties,” she said out of the blue.

“Yeah, you got me good,” I reluctantly agreed.

“No. I mean, they all got to see you in them. I guess ... you know ... I’d kinda like to as well.”

I know what you’re thinking: does that really sound very likely? But it seemed pretty plausible to me at that time - I mean, what girl wouldn’t? “Are you serious?” I asked.

“Yeah. I am. I’ll tell you what, if you do, I’ll let you see me ... In mine! In mine! Not yours! Ugh!”

I guess that alarm bells should have been ringing and sirens wailing, but all I could think about was seeing Izzy in her underwear, and I was already getting hard. “OK, deal,” I agreed.

She led me to her room and picked out a tiny pair of lemon-colored panties with a cute white bow at the front. When she saw my expression, she said, “They’re really stretchy,” and demonstrated by pulling her hands apart.

I took them from her, and she stood there, looking at me. “Do I get to watch you change, too?” I asked, not sure what answer I really wanted to that question.