In The Spongebob Squarepants Movie (2004) we see at one point during the final song a guitar solo wich we see a non cartoon guitar for a couple seconds. So that mean
Spongebob playing guitar by bobandpotato on DeviantArt
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SpongeBob Squarepants: Guitar Songs, Songs for a Duck at Sea (Interactive Music Book): Sherm Cohen, Nicholas R. Jennings: 9780785384441: Amazon.com: Books
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