A random inanimate object you need the apprentice technician to grab but don't have time to call it by it's native name because of ridiculous overhead production demands.
Hurry up and grab me that Jimmy-Jammer Jr. So I can get this torque converter dislodged.
Similar to a monkey or a pony, a Jimmy is used to refer to an amount of money - in this case £100,000. It originated in Glasgow slang in the early part of this century.