v.1. To make a mistake, especially out of confusion or ignorance: He tried to tell the joke, but he flubbed up the punch line. She is nervous about giving the toast and will probably flub it up. My taxes were incorrect because my accountant flubbed up.
2. To cause someone or something to blunder: I tried to hold my camera steady for the shot, but all the insects buzzing around flubbed me up. The constant distractions flubbed up the actor.