When I was in high school in 2011, I was in the same band class as my crush and we were the only two trumpeters in that class. He was a huge flirt, and so kind of to indulge him I'd contradict him at every opportunity. One day, the band teacher was explaining something about part of a piece we were playing, and the crush said, "He's gonna call it a polymetric sesquialtera [a music term meaning "two time signatures occurring simultaneously"]." I contradicted him, and the band teacher did, in fact, call it a polymetric sesquialtera. From that point on, that phrase was an automatic argument-winner for my crush and he actually used it on a regular basis. I decided it was necessary to kind of honor that by making my username on another forum I frequent into Polymetric Sesquialtera. I used it as my tumblr URL, but then I got bullied off tumblr and decided to rename myself on all the places where I went by Polymetric Sesquialtera in order to avoid people possibly making the connection and bothering me again. I really liked the idea of having a music term as a username, though, so I went to a page of Italian music terms and tried to find one that could work as a username. Altissimo was what I got. (It refers to the highest register on woodwind instruments, even though I play the trumpet.) Then, when I signed up for these forums, I decided to use the same name.
Great story, right.