It just gets better and better as it goes along.
This from a friend of mine (who actually had the conversation)
(FYI: the Tyne & Wear Metro is the Geordie tube)
Her: We're staying at the Holiday Inn at the MetroCentre. So we'll catch the Metro into town.
Me: No you can't.
Me: The Metro doesn't stop at the MetroCentre.
Me: It doesn't go there.
Her: So how do I get into the city centre?
Me: You catch the train.
Her: So it does stop there.
Her: The Metro.
Me: No. Trains stop there.
Me: The Metro!
Her: So I catch a train.
Her: Not A Metro.
Her: Is the Metro a train?
Her: So I catch the Metro.
Her: But Metros are trains!
Me: BUT NOT ALL TRAINS ARE METROS!