Possible Clues:

• Implausible
• Unlikely
• Strained, like Indian tea is?
• Unconvincing
• (Tale) hard to believe
• Hard to swallow, like imported kangaroo meat?
• As hard to swallow as potatoes, originally?
• That's not near to being likely
• Fellow with the red face not entirely embarrassed? Unconvincing!
• It's not probable that it was brought from such distance