Possible Clues:

• Unprepared to give a daughter party
• Bit of stage creativity
• It's not scripted
• Stage make-up
• Perform in the Upright Citizens Brigade, say
• Wing it, verbally
• Robin Williams comment, maybe
• "Whose Line Is It Anyway?" line
• Way to disorient one's co-stars
• "That's not in the script!" evoker