The strings contain "sqli" which some of the posters inferred to mean they were experiencing a SQL injection. I doubt this is actually the case. I will say, though, that I have a Brother printer like the one described where I work and have seen similar odd strings on papers that come out of it. At least one time, it's just printed gibberish. I think the common denominator is that these printers are openly shared on a network with a public IP (at least mine is...it's at a big University with public IPs fore everybody). I don't know if this is related or not, though.
Seven hours after posting, I've racked up 21 points for this comment.
I think this shows a defect in the blind voting we've had here for the last year or so. There's no way this off-hand comment is worth that much karma, but nobody can see that I'm being overcompensated for it.