Which accidental invention was originally marketed as a 'failure' called the 'Silver Lining' before becoming wildly successful once rebranded?

Some of history's most revolutionary products were discovered completely by accident! These fortunate mishaps led to inventions we now consider essential. This trivia will test your knowledge about the surprising origins of everyday products and the marketing stories that launched them from laboratory accidents to household names. Do you know which famous invention was originally marketed as a complete failure before becoming an iconic success?

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Post-it Notes (originally a failed super-strong adhesive)
Coca-Cola (originally a failed headache remedy)
Penicillin (originally a failed laboratory contamination)
WD-40 (originally a failed rust-prevention formula)