Possible Clues:

• “Whose Line Is It Anyway?” style
• The speaker's for and against ad-libbing
• Finish off better stand-up routine
• Technique taught at the Groundlings and UCB
• Ad-libbed comedy
• Specialty for many college acting groups
• Comedy style based on 'yes, and'
• Unscripted comedy, informally
• Finish off better stage technique
• Second City specialty