Green’s Dictionary of Slang

1. (also flub up) to botch, to bungle, to make a mess of.

1924		P. Marks Plastic Age 122: I have a feeling [...] that I have flubbed this talk.
c.1930		N. Kimball Amer. Madam (1981) 152: I’ve known all kinds of men, good and bad at it in the sense of enjoying and performing, or flubbing it and being miserable.
1947		E. Condon We Called It Music 120: Mezz had a couple of breaks to take on his tenor saxophone during Eccentric. Somehow he always got nervous and flubbed them.
1953		J. Thompson Criminal (1993) 51: We’ve flubbed a good story.
1958		Murtagh & Harris Cast the First Stone 210: ‘Give her a chance, one more that’s all, and if she flubs this we’ll both wash our hands.’.
1960		G. Swarthout Where the Boys Are 189: When Piston [...] would flub a point he would throw himself bodily against the screen.
1967–8		Baker et al. CUSS 119: Flub To do poorly on something [...] on an exam. Flub up To do poorly on something.
1977		Fidrych & Clark No Big Deal 33: ‘[T]hey flubbed up. They gave me a draft card sayin’ I was good. Then a month later they gave me another draft card sayin' I was no good’.
1978		S. King Stand (1990) 164: They’d had a chance [...] and flubbed it.
1989		M. Amis London Fields 122: It was like the fifteenth rehearsal with some dud leading man who kept on flubbing his lines.
1993		L. Rodríguez Always Running (1996) 193: The bikers got on the stand and flubbed their testimony.
2003		J. Lethem Fortress of Solitude 274: The disc jockey flubs the call list.
2014		E. McNamara ‘Authenti City’ in ThugLit Sept. [ebook] You would have flubbed your lines and lost your nerve if you knew he was serious.

2. to waste time, to fool around.

1950

B. Spicer Blues for the Prince (1989) 166: If he starts flubbing around [...] bring him in.