fork over - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Also, fork out or up. Hand over, pay up. For example, It's time you forked over what you owe, or He forked out a hundred for that meal, or Fork up or we'll sue. [Slang; early 1800s]