Definition:
To be full of energy. To be prepared for any eventuallity; to be over-prepared.
Usage:
"Boy, Sam is loaded for bear today!"
Explanation:
When hunting bears, or carrying a firearm to defend oneself against bears, one has to load the weapon with large calibre/high energy ammunition. Thus, literally speaking, being 'loaded for bear' means someone carrying a weapon that is loaded with something powerful enough to kill one. The phrase has come to mean that someone has lots of energy. Can be positive: someone is feeling energetic and confident enough to wrestle a bear. Can be negative: someone is very angry and prepared to unload a lot of emotion on a person.
