rusty

adjective, colloquial, of a person: bad-tempered, irritable; angry (“rusty, adj.3 and n.2.” OED); note that the reference below is to bees, not people

“You very seldom get stung when they’re swarming. You can stick your hand right into the middle of them. As long as you don’t squeeze one of them, they won’t whack you, but the time they’re rusty is when you’re taking honey off.”