stupid, naive, uninformed, and unaware of the ways of the world - with the turnip truck metaphor, the implied background reason is because you are a rube, a country bumpkin, who just got into town from the countyside comparable is "just get off the boat", but the implied reason for your cluelessness there is because you're foreign and just arrived from abroad

This is an idiom that means someone is stupid. I don't know the idiom's history or why it's a turnip truck vs. a cabbage truck, etc., but this is the meaning.

it means you're crazy. ;D (\(^-^ )/)

This is an idiom used to show the difference between people from rural areas and people from cities in the USA. It is said to have originated around the mid 60's and that Johnny Carson, a tv host in the 1960's, may have been the originator, if not the actual originator, he was definitely the person who made it popular with his continual use of it on his tv shows.