Barcode tattoos aren't uncommon any more. UPC barcodes are the most common bar code tattoo subjects and barcode tats are often found on the back of people's necks.

Some believe barcode tattoos to be a sign of the apocalypse speculated about in the Christian Bible which states people will "receive a mark in their right hand, or in their foreheads: And that no man might buy or sell, save he that had the mark of the beast" :)