it occurred to me years ago, as self checkout aisles just started to proliferate, that something like this could happen.
i finally heard it in person yesterday at the local superfresh.
the guy ahead of me bought some a bag of nuts, 'loose' as it were--the kind that you bag yourself and need to be weighed.
he placed the bag on the scale/scanner.
a second later, the self checkout machine voice said, "please remove your nuts from the scanner."
http://en.wikipedia.org/wiki/Self_checkout