NAIVETE

As an Englishman living in America, there is a plethora of words and phrases I have never known before, many of which are very amusing to me. When I first arrived I remember trying to phone a friend at work.
"Hi is Mark there, it's Chris Standring?"
"No I'm sorry sir he's out in the field".
"He's what?" I said.
"He's out in the field, I expect him back later today".
"What's he doing in a field?" I asked somewhat perplexed.
"He's seeing clients" she replied.
"In a field?" I asked.
"No it's just an expression sir", she said, a little amused by my alien disposition.
"Well OK I'll call back later then".
I hung up scratching my head, just a little embarrassed.