I have a wanking story, but it isn't awkward, or at least it wasn't to me. It's Harry Potter/fanfiction related too.
One time in probably junior or senior year of high school, I did a rare thing and skipped class. I slipped into the dark auditorium and looked at a favorite porny Harry Potter fanfic at the time, and wanked. It was awesome, one of my coolest stories from high school, but not one I really tell many people. :-D
It was Malfoycest too. ;-)
...In sophomore year, I had a boyfriend for a couple months, and we totally got frisky and kissed and groped in the most awkward places, so I guess that's more on-topic. Places like a school stairwell, an elementary school playground, and our school bus. Definitely regret all that.
Don't regret the wanking one bit, though! But no one was around for that.