Possible Clues:

• Kit Kat bar slogan ... and hint to the starts of the answers to starred clues
• *"Oh, puh-lease!"
• 'Jeez, lighten up, will ya!'
• Losing tennis player's prayer?
• "You gotta be joking!" and a hint to the last parts of 21-, 31- and 42-Across
• 'You have got to be kidding!' (or a hint to solving eight theme answers)
• "How stupid do you think I am?!"
• 1980s Nell Carter sitcom, and a hint to the puzzle theme found in the ends of 17-, 32-, 39- and 46-Across
• "Aw, come on!" (and this puzzle's title)
• "How dumb do you think I am?!"