- [guf ]1. n. a foolish oaf; a goofy person.□ Sometimes I’m such a goof. I really messed up.□ Don’t be a goof. Get with it.2. in. to use heroin or some other addictive drugs without intending to become addicted; to play around (with heroin). (Drugs.)□ Gert spent the first few years just goofing.□ She was goofing, and you know what that leads to.3. in. to scratch, nod, and slobber after an injection of heroin. (Drugs.)□ She just rocks and goofs for hours.□ She has been goofing for an hour.4. AND goof up in. to make a blunder.□ Whoops, I goofed!□ This time, you goofed.5. n. a blunder; an error.□ Who made this silly goof?□ This goof is yours, not mine.
Dictionary of American slang and colloquial expressions. 2015.