Automotive: A tool commonly used for breaking the tapers loose on ball joints and tie rod ends. Sometimes called an olive fork. They are correctly called a "Ball Joint Separator" or "Tie Rod Separator" but have gained the name from their resemblence to the long, skinny forks used to remove pickles (or olives) from a jar.
The term can be used for a variety of items, anything much longer than it is wide, with two prongs on one end and some sort of handle on the other.
"I need to replace a tie rod end on my car but I don't have a pickle fork. "
"Any ideas how I can separate these flanges?"
"Have you tried a pickle fork?"
"No, great idea!"