Writing Prompt: Climbing Trip

I got some good feedback on my Hermione story here a while back. That post was a response to a writing prompt on kitg. Unfortunately, the writing prompt idea didn't really take off there, but I was hoping that it might have more success here. If anyone is interested: here's a prompt I came up with.

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Before their freshman year, the students at Penbrooke highschool were sent on a supervised day trip to a local ropes course. The various activities were billed as "team building" for the incoming class. Currently, the students were watching as the instructor, a pretty blonde woman in her mid twenties, explained how to properly put on the harness.
"...then you're going to step with one leg into each look here" she explained and then looked up seriously.
"This isn't as big a deal for you girls. But boys, it's very important that you tighten these straps properly and also that you..." she coughed nervously "adjust yourselves so that the straps aren't pinching or catching anything. If your harness is too loose or you put it on wrong, it could put a lot of pressure on some pretty tender parts if you fall. I don't need to explain to you how uncomfortable and embarrassing that would be"
All the boys in the group looked away, and most of the girls giggled a bit. Olivia, Sarah, and Ellie, however, grinned wickedly to each other. Sarah, a petite brunette, whispered to her friends "I'll bet we could put some pressure on some tender parts. Watch this."
As everyone finished putting on their harnesses, Sarah looked quizzically at each crotch until she found what she was looking for. Everyone scampered up onto the ropes course, and Sarah climbed up next to Noah whose harness wasn't quite properly adjusted. If he didn't fall it wouldn't matter, but with just a little push...