* Slang for "joke" is often informal: It's hard to find a slang term for "joke" that would also work as a palindrome. Palindromes are usually formed from more formal words.
* Palindromes are symmetrical: They read the same forwards and backward, limiting the word choices.
Here's a playful attempt, though it's not a true slang term:
* "Yay" - While not slang for "joke," "yay" is a word that expresses joy, which is often associated with jokes. It's also a palindrome.
Let me know if you'd like to try a different approach! We could focus on a different slang word or explore a more creative solution.