Stems from the word "Fumble" in football, in which a player loses possession of the football. Almost always occurs during moments of acute stress specifically when the desired end-state of a situation is within the grasp of an individual but then victory slips through the fingers of the fostering individual resulting in disaster.
1) Dude why did you just foster the christmas turkey on the floor? Now we gotta eat spam covered with brown sugar instead.
2)All he had to do was juke the Florida Safety and he would have had 6!!! But he lost his emotions and effing tossed the ball into the stands, fostering the game away.
Game over, Florida Tatters our windsock again...
Sam: Yeah I know, he's getting alot worse.
Ethan: Ah well, better let him get it out of his system.