A phrase originated from 19th century Thailand, which is often used today to describe something being weird or abnormal.
John - "Did you see that weird guy at the store?"
Mary - "Yeah, he was Knocking At The Cow's Door."
A saying from the 15th Century, which peasants used to tell when curfew began. Cows would release a "cry" when they felt tired, which usually happened near the normal curfew time. People use this phrase nowadays to signal distress or if someone bad or unlucky happened to them.
John -"I lost my wallet at the park earlier..."
Mary - "Well, When The Cow Cries, The Day Dies."
Used in the 1800s to describe something being silky/smooth. It is often used nowadays to describe something being suspicious.
John - "Did you lie to her?"
Mary - "No..."
John - "*scoffs* Like Silk Made Of Fresh Milk..."