My uncle was a tour guide in Iceland some time ago. He once guided a group of Americans around the country and stopped at a glacier in the middle of nowhere. He explained to the group that this glacier had been here for thousands of years and that it doesn't melt. The group then went back to the bus to carry on, but my uncle notices that a woman was carrying a big piece of the glacier towards the bus.
So, he stops her and says, 'I'm sorry, you can't bring that onto the bus, it will melt.'
The woman quickly responded, 'But you said it doesn't melt.'
My uncle stood there for a while, dumbfounded by the amount of stupidity that was in that answer, before finally saying, 'Okay, but you'll have to put it in your backpack and keep it in there for the whole journey.'
The woman readily agreed and started to empty her backpack to make space for the big block of ice. Needless to say, this didn't end well for the woman, as the ice obviously melted in her bag