A young man went to his grandfather's place to stay for the weekend. He was sitting down to lunch when he noticed that the spoons and forks were encrusted in a thin filmy substance.
He asked his grandfather,"Are you sure you washed it properly?"
"As clean as cold water can get it" was the reply.
So the young man shrugged and started eating.
The next day at breakfast he noticed that the plates were dirty and grimy. It also smelled a bit like dog.
Are you sure you washed it properly?"
"Clean as cold water can get it" was the reply again.
The man, a bit suspicious for his health, looked at his grandfather, than at his plate and started eating.
As he was leaving, his grandfather's dog jumped out in front of him, growled and generally blocked him from going forward.
"Cold water, leave the poor boy alone!" shouted the old man from inside.