Related Clues:

• Chatter thoughtlessly
• Tell everyone
• Pretend or divulge
• Spill something
• Allow aboard
• Tell (on)
• Rat, so to speak
• Be a squealer
• Allow to board
• Have a big mouth
• Ruin the surprise
• Give away a secret
• Rat someone out
• Betray a confidence, perhaps
• Be a rat fink