born yesterday (?.)

• artless
• bluff
• blunt
• candid
• childlike
• confiding
• direct
• frank
• guileless
• ingenu
• ingenuous
• innocent
• naive
• open
• openhearted
• outspoken
• plain
• simple
• simplehearted
• simpleminded
• sincere
• single-hearted
• single-minded
• trustful
• trusting
• unguarded
• unreserved
• unsophisticated
• unsuspicious
• unwary