on the hop

prepositional phrase3

1. •
   Unprepared; unready and unable to deal with something.

   • "Tough," said Peter. "Very tough. I have a chance if I can keep him on the hop till his weight and short wind come against him—in this hot sun too. To tell the truth, I haven't much chance else. […]" — 1951
2. •
   (Ireland, slang) Playing truant from school.

   • Judy: A couple of times I went on the hop. — 1995
3. •
   Spontaneous; unplanned.