Meaning: When a drug starts to take effect
Example: Her hayfever didn't feel half as bad once the antihistamines had KICKED IN.
Meaning: Break something with your feet
Example: They KICKED his head IN.
Meaning: Contribute money
Example: Iíll KICK IN for some of the beer if you will buy the pizza.
Meaning: Start having an effect
Example: The budget cuts are starting to KICK IN and people are struggling.