Related Clues:

• Put a muzzle on the joke
• Muzzle in palindrome form
• Joke or muffler - a palindrome
• Trick or prank
• Silence the joke
• Either way, that'll stop you giving 25 down
• It's so funny it leaves one speechless
• That's a funny sort of conversation-stopper
• The joke is it's such a conversation-stopper
• Funny how either way it puts an end to conversation
• Funny sort of way to stop talking
• The sort of joke that's a conversation-stopper
• Either way, a conversation-stopper
• Conversation stopper
• Jokey sort of gift