foo goo Share definition Flag (Note: Two words): Any small unidentifiable residue, globule, or spill, usually sticky or crusty. "Jenny, I'm not lending you my phone any more. It had foo goo on the face that I had to scrape off. Were you eating fried chicken or what?" foo goo by al-in-chgo October 6, 2013 0 0 Get merch Get the foo goo mug. Buy Now — $32.95 See more merch