Possible Clues:

• Gooey, goopy fun stuff
• Snail substance
• Scoundrels, so to speak
• "Ghostbusters" hazard
• Scuzz
• Oozy substance
• Goo that helps snails to move along
• French boy's looking up meaning of 'gunk'
• Goo in some oddly satisfying videos
• Yucky stuff