Certain routine events just happen with little thought and little in the way of expectations. This is usually true of a trip to the shop for some Brillo pads and loo roll.
Homeward bound and waiting patiently for the green man to appear and guide me safely across the road, I was taken by surprise when two men sauntered over, said hello and invited me to a party.
The correct response was probably something like "Not on your f***ing nelly, mate!"
My response? "Sorry, I have a chicken in the oven."