A good non sequitur is like a good joke: both of them build up your expectations, then unexpectedly upend them. My back-up TV viewer had my back the other night when he hit the record button after watching the first few minutes of a 1936 gangster film called Bullets or Ballots. A character was trying to think of the name of "that publisher who was murdered, the one named... uh, the name..." (It was a front-page story in the newspaper since the victim had been the leader of the city's vice squad.) "A–B–C–D," the man mutters. "E–F–G–H–I–J–K... Bryant!" This is a riff on a mnemonic device that I often use myself, whereby if I can't remember a person's name, I just start flipping through my mental Rolodex, silently saying the alphabet to myself. Most of the time when I come to the letter the person's name (either first or last) begins with, it suddenly jumps out at me. It's kind of amazing how well this works. (Although my friend says he knows of no one else who does this, it turns out my sister does it, and I'm sure other people must do as well.) Another nice example of the non sequitur was to be had the other day at work when I overheard one of our students complaining that "all of the streets in downtown Albany sound alike! Eagle, Dove, [here one might have added Swan, Lark, Quail, Partidge, or Robin]... Hamilton," he concluded dourly. Like bullets or ballots, one can go either way with the foreign phrase non sequitur. But the right way for you to go is with a U. We found one example of this typo (or misspelled Latinism) in OhioLINK, along with 19 in WorldCat.
(1936 theatrical poster for Bullets or Ballots, from Wikimedia Commons.)