This happens when a person is speaking and either repeats a syllable or two, or even a grunt-like noise, in place of an actual word, and of courseyou know what they are trying to say, but you need to wait. A general nervous or anxious person. Thus, they are a flumberbuck!
Fluber dinkle is uasualy the name of an umpire or coach of a sports game, the children in the team generally shout at him that he's on nugget duty. If he disagrees you get your main firework guy (uasualy called Thomson) to blow him or his car up !!
Alternate definition: to hit, throw, or send flying. To move ungracefully.
This definition has been around for seemingly decades, though nobody is quite sure of it's origin. Some believe it derives from the english word 'blubber', known for being squishy and bouncy, and the word 'bonk'- to hit or tap ungently.
"When Brian told me about that new article, I was totally flubberdonked!"
"She came over to me and flubberdonked the bookright out of my hand."