Related Clues:

• Gave earnest assurances
• Gave one's word
• Gave testimony
• Insisted absolutely
• Used colorful language
• Promised
• Insisted
• Execrated
• Blasphemed
• Placed a hex on
• Talked like a sailor, stereotypically
• Risked getting bleeped
• Risked an FCC fine
• Talked X-ratedly?
• Took oath or cursed