A re-purposed military term used in its new context to describe a particular cuisine or article of food that greatly increases the urge to poop, or increases the time spent pooping.
"Man, I love this Chinese Buffet, but it's a real force multiplier on the ol' colon."
"How was the BBQ?"
"The ribs were epic, but oof"
"Force Multiplier?"
"You know it, dude."