v.1. To make a mistake, especially out of confusion or ignorance: You really goofed up by not telling your parents you were leaving. I didn't follow the instructions for the job carefully, so I goofed up.
2. To cause someone or something to blunder: The directions to the park were confusing and they goofed me up. You're not alone in getting lost; that fork in the road goofs up everybody.
3. To perform something badly; blunder in executing something: You really goofed up the spelling section of the test. The band didn't rehearse enough before the concert and really goofed the march up.