Yes, these are (apparently) all true.
A circus owner walked into a shop to see everyone crowded around a table watching a little show. On the table was an upside down pot and a duck tap dancing on it.
Dr. Laura Schlessinger is a radio personality who dispenses advice to people who call in to her radio show.
This concerns a question in a physics degree exam at the University of Copenhagen: "Describe how to determine the height of a skyscraper with a barometer."