After reading through this thread and trying to think of a good story, I think I have one...
When I was in high school, I was what could only be described as "whipped" by my lovely little high school girlfriend, who was kind enough to let me see her naked and such. As such, I met her by her locker at the end of class every day.
My locker was at the end of the hall and hers was on the opposite wall, maybe 20 feet down the hall. On that particular day, she had been wearing black jeans (hey, black jeans used to be cool, right?) and a red sweater. So, I had seen her at her locker and finished up emptying my backpack into my locker so I could spend a few minutes with her.
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A quick interruption to help build the story. When I was in high school, there was a beautiful girl of Mid-Eastern descent that was Islamic. She was really a great all around girl (not suprisingly named most beautiful girl in our class, in fact) that was intelligent, very friendly, and just a total knockout. Because she was Islamic and had very strict parents, she was never allowed to date or go to football games or out in groups. On top of that, she had a body-building, older brother that made Lou Ferrigno look like a peanut. Rumor had it that he had listened to a telephone conversation his sister had with a boy that wanted to take her to a dance, and the ensuing events were not pretty.
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Back to my story now. I finished up with my locker and slammed it shut and headed over towards my girlfriend's locker. Since she seemed engrossed in packing her books into her backpack, I snuck over and, as I regularly did, tickled her ass, just to the inside of her back pocket.
What happened next is kind of melted together and I can't remember in which order they happened, but I think the next thing I saw was my girlfriend appearing to my right, walking with my bestfriend towards her locker. Realizing that I could not be tickling my girlfriend's ass with my lefthand because she was clearly standing to my right, I turned to see whose ass it was that I was tickling, and sure enough, it was the beautiful girl of Mid-Eastern (I know, lame description, but since I am still very much afraid of her brother, the less detail the better
) descent's rear end. There last names both began with the same few letters, so, of course, their lockers were adjacent.
She jumped and, fortunately for me, began giggling. My girlfriend, who caught me in the act, was suprisingly not angry once she realized that they were both wearing black jeans and a red sweater and were about the same body size with similar hair color/styles. My best friend, predictably, enjoyed being able to see me act like a big ass.
The whole thing was pretty surreal, because at the time I was so afraid of her brother and sexual harassment (around the time Clarence Thomas made it "popular"), plus she had never dated anyone, so I felt bad about even touching her.
Looking back at it now it is pretty damn funny, but still embarassing.