Covered with, filled with, or clogged by guck; made messy or sticky.
From guck + -ed (past participle/adjective suffix). A recent formation following standard English verb patterns, emerging in the 1970s-1980s.
Gucked is a perfect example of how English speakers instantly turn new nouns into verbs and adjectives—we can instantly understand 'gucked up' even though it's only been in common use for 50 years.
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