High school, computer info & science class.
It was the last day of the semester, and everyone was already done everything. One of the students was given permission to bring in their Wii, and he was also bringing in Brawl. And we were going to have a tournament.
Out of everyone I knew locally (which wasn't too many people), I figured I was probably well up there in Smash games. I could beat all my friends at least in Melee, though I didn't know about literally any technique other than basic fighting.
Which wasn't a problem. I picked Marth, who I typically did my best with, and I was generally kicking ass.
Except for one problem. They had smash balls on and I typically played no items. I vaguely recall it being double elimination and that I SD'd myself to death both times with Marth's final smash.