An exclamation used to show anger or being upset when somebody fucks something up when it looked like you were so close to succeeding. Usually a team thing. Derived from Nick Folk, the awful kicker for the Jets.
Jim: Steve and I were up till 2:30 but our presentation is really good! Right Steve?!?!
Steve: Oh shit I forgot it!
Jim: Wow you just Folked it didn't you...
Steve: I'm sorry!
Jim: I can't believe he Folked it!
Jack: I know what a scrub