Spying On Sister And Her Friend

I wrote a while ago about my first experience with a girl, when my sister's friend Katie entered the pool shower and on a dare and gave me my first handjob. This has me reminiscing on other experiences, as me and Katie fooled around on multiple occasions over the next several years, and I experienced many firsts with her. I'm now going to tell you about my first voyeur experience.

When I was 16, I lived in a small house with my mom (a single mother) and my older sister Erin (17). We were poor and had a small house with 2 bedrooms and one and a half baths, with my mom having the master bedroom and bath and my sister and I sharing a small bedroom with the half bath. The most spacious room was the basement, which became a kind of game room for when my sister or I had friends over. We had an agreement not to bother each other during this time.

One Friday night, a few days after the shower incident, Katie came over to see my sister while I was helping my mom with after-dinner clean up. As I was washing the dishes and my mom was packing up leftovers, Katie entered the kitchen to exchange pleasantries with my mom. When my mom's focus was on her task, Katie came up behind me, grabbing my butt with one hand and my crotch with the other, giving each a couple of pumps. I stifled a moan and instantly started to get hard with only my second time being touched by a girl, the memories of the first still on my mind. Katie stopped before my mom noticed, thankfully. I stayed facing the sink so my mom wouldn't notice the tent and Katie dismissed herself to go see my sister downstairs. My wood wouldn't go down, no matter how much I focused on the dishes. Thankfully when I finished my mom told me to take out the trash as my last chore. I was able to hold the trash bag in front of me and conceal my erection as I went outside.

 I walked around the side of my house where our trash cans were. Next to the trash cans was one of those small basement windows. I was nosy, and took a peek, curious about what they were up to and always willing to get a glimpse of Katie's DD tits, which were prominently displayed by her tight tops. What I saw shocked me. Katie and Erin were kissing on the couch! Naughty Katie, she was going after two siblings at the same time! I crouched by the window, unable to focus on anything else now. I knew Katie was bi and always up for fun, but my sister had never expressed interest in girls. They started making out more passionately and started to grope each other over their clothes. I couldn't resist, I unbuckled my belt and slid my pants down, and pulled out my still-hard cock. It was dark out, and there was a fence behind me to the next property so nobody would see me. I knew from all my nights in the basement that with the light inside, there was no view out that window, and with the girl's music as loud as it was, they wouldn't hear me.

I slowly stroked, enjoying the view. Katie stripped her shirt off then undid her bra. I watched as Erin started kneading them, almost jealous of my big sis, I knew how good those tits felt. Katie was 5'0'', plus-sized, blonde with the big tits. Erin? She was 5'5'', slim, brunette, with maybe B cups. They had very different bodies. I then watched Erin take Katie's nipples in her mouth and suck them. I wasn't going to last long at this rate. Then Erin removed her shirt, and having been braless, they were both now topless. They switched and Katie started sucking Erin's nipples. Sharing a bedroom and bathroom, Erin and I had caught many glimpses of each other over the years, to the point we didn't blink twice if we walked in on each other changing or had something poking out in the morning when waking up. We'd seen each other's whole bodies by this point, but I'd never had a sexual thought of my sister before. I felt some guilt, one spying on a private moment, two feeling sexual attraction to my sister, which I knew should be wrong. Watching her moan as Katie sucked her tits though? Too much. I exploded all over the grass in front of the window. 

In my post nut clarity, I noticed I had been outside way longer than it takes to take out the trash. I quickly ripped the bottom of the trash bag, letting some smaller trash fall on the ground, and then dumped loose items in the can, putting the tattered bag on top. I took one last peek through the window, the girls were making out and grabbing each other's tits again. I made a note for the spank bank and headed inside. My mom asked where I'd been. I replied that the bag broke and it took a while to get all the contents cleaned up. She made a remark that we would get some sturdier bags next shopping trip. I then retired to the bedroom to read. 

A couple of hours later, Katie left, and we all said goodbye. My sister sat on her bed to read, and didn't notice her nipples were still hard, poking through the fabric of her shirt. I grabbed my clothes and a towel and went to shower, knowing that I had to get out of there. I jerked off a second time in the shower. I changed into pajamas, and went back to our room, where Erin had the lights out. I climbed into bed and fell asleep fast. I dreamt of what I'd seen the previous evening. I awoke to her closing the door on the way out in the morning. I noticed I had kicked off my blankets during the night, and my morning wood was sticking out of the hole in my sleep pants. It wasn't the first time it had happened. It was usually just slightly embarrassing, but it felt extra naughty that day, with her being part of the reason for that wood, and not even knowing it!