catch on

catch on  {v.},  {informal}

1. To understand; learn about. — Often used with "to".

You'll catch on to the job after you've been here awhile.

Don't play any tricks on Joe. When he catches on, he will beat you.

2. To become popular; be done or used by many people.

The song caught on and was sung and played everywhere.

3. To be hired; get a job.