Maybe that’s what he thought would catch one’s eye…like what happened to you 
hehe
Perhaps that’s bit of trivia gave Law & Order: S.V.U. the idea for this episode. Acceptable loss - Wikipedia
Q, I always enjoy your anecdotes about your work.
I think in the novelization of “Aliens” the marines (or maybe Bishop?) are described as having barcodes on the back of their necks. That’s mid-80s there.
C of E Bishops have their diocese tattooed on the back o’ the neck. That was in the 70s, before the ubiquity of barcodes.
This is what I pictured.
Anyhow, I know a few hard-core geocachers who have tattoos featuring a tracking number that can be logged on the geocaching website. This is one example. Search for ‘trackable tattoo’ for others.
Please “write” a paper about it for some medical and/or criminology journal, with loads of pics. If you can’t come up with a spurious justification for the paper, take the pics and send them to me and I’ll make something up. I’m thinking “tatoos in prison - implications for the treating doctor”.
That’s how to do science!
Edit: This is why this forum really needs to have a facility to display images.
If you can’t find those sorts of images on your own with the whole 'net at your disposal, you’re just not trying.
Fezzes are cool. Bow ties are cool. Toasters aren’t cool until the Doctor says they’re cool.
StG
Back when I was in college I remember standing in line at the grocery store one day behind this tough looking, muscley guy. It took me a moment to notice the tattoo on his bicep. There, smiling happily in his bathtub, pink as can be, was Mr. Bubble. To this day I wish I’d asked what the story was.