jump on

verb3

1. •
   To board a vehicle.

   • Jump on a nº9 bus, and it will take you more or less to the door.
2. •
   To take immediate action regarding; to avail oneself of without delay.

   • Community banks can jump on the opportunity to make changes. — 2003
3. •
   To attack verbally, to criticise excessively.

   • I hate the way she's always jumping on me for the slightest little mistake.