Is there any special meaning if one repeats "word" twice?
Native speaker’s answer
Rebecca
"Word" here is slang for "I understand". Therefore, Jake is emphasizing that he understands what Princess Bubblegum is saying by saying "word" twice. "Word" used as a slang term was more common in the past, but is not common anymore. Ex: A: Let's meet at the mall tomorrow, okay? B: Word.