Prepared for an imminent activity. Believed to have originated during WWII, referring to the M1 Garand rifle, whose bolt automatically "locked" a round in the chamber when the rifle was "loaded" with a magazine, which could then be immediately fired without any further preparation required.
by 8david8 March 11, 2016
A slang term to describe the pleasurable moment when you realise you've scored and you'll shortly be on your way home with a chick for a bit of action!
As Dave left the bar with his girlfriend, his mates asked where he was going. He simply said "I'm locked and loaded, and good to go!"
by DC July 14, 2004