kick in

verb8

1. •
   To kick; to collapse or break by kicking.
2. •
   To start, connect, or take effect, especially in a sudden way; to begin functioning.

   • You have to push the switch hard to get the heater to kick in.
   • I took my medication an hour ago, and it hasn't kicked in yet.
3. •
   To join or begin.

   • You should kick in on the work.
   • The rhythm section will kick in after that point.
4. •
   To kick or strike so as to cause the object struck to collapse or fall inwards.

   • Upon hearing residents in the burning house, the passerby kicked in the front door and yelled to those inside.
   • You touch me again, I swear I’ll kick your teeth in.
5. •
   To contribute, especially to a collection of money; to hand over.

   • For the year-end party, we're asking each employee to kick in twenty dollars.
   • This is a worthy charity, so everyone should kick in.
6. •
   To begin, contribute or join in on.
7. •
   (slang) To kick or strike (a person); to beat up.
8. •
   To die; to give up on something.

   • The business is going to kick in most likely.