Definition of before one can say Jack Robinson in English:

before one can say Jack Robinson

phrase

informal
  • Very quickly or suddenly.

    • ‘Yet, with a ton of people assigned to wait on customers - eight clerks were politely servicing people - I had my onion bagel with vegetable tofu spread and a juice before one could say Jack Robinson.’
    • ‘Fin has promised to invest the dough so that the boys will become millionaires "before you can say Jack Robinson".’
    • ‘The canoe slides into the water in the blink of an eye and before you can say Jack Robinson it's twenty yards off shore.’
    • ‘Foot to the floor and before you can say Jack Robinson you've crossed the finish line having attained a speed in excess of 300mph in a quarter mile!’
    • ‘A friend of mine in Brixton kept koi carp in a raised toilet and this heron came straight in and ate the fish before you could say Jack Robinson.’