jump in

verb6

1. •
   To enter something quickly, usually a mode of transport.

   • I jumped in the car, and we sped off to the meeting.
2. •
   To join in on an activity quickly.
3. •
   To interrupt someone while they are speaking.
4. •
   (US, slang) To initiate into an organization, usually a gang, with violence.
5. •
   (slang, old-fashioned) To ambush (someone).
6. •
   To play a card that matches the top card in the discard pile out of turn.