Going to see a man about a dog

 
I always thought the expression "I'm going to see a man about a dog", used by my Dad, was his own invention. But I have just come across it in a book of catchphrases. Dad would use it when asked by me where he was going on a Thursday night - his night out when he went to the pub for a game of darts. An alternative phrase used by Dad was "Going to the woods to pick bluebells".

Going to see a man about a dog is an excuse offered if one wants to be discreet and cover up the real reason for doing something - often some nefarious activity or an activity to which it would be impolite to refer in mixed company - such as going to the loo. The phrase is said to derive from the days when betting on greyhound racing was illegal.