When you know you messed up.

[Highpower]

I was cured of wearing a ring while working after going through tech school in the USAF. We were shown all kinds of (very graphic) color pictures of injuries that were treated in various base hospitals that resulted from jewelry getting snagged on something. We saw fingers that were peeled clean to the bone all the way up to the third knuckle. One poor soul tripped going down a loading ramp and tried to grab the hand rail, only to get his wedding ring hooked on a fastener. Gravity did the rest.

The rule on base was NO jewelery was allowed when working. The only exception given was for wedding rings - but if you decided to wear it, it HAD to be completely wrapped in tape along with the finger.