Hi! It means to get over having head lice. To be cured from the condition. In your example, no wants a person with head lice to use a comforter because the lice will get onto it and pass itself to anyone else who that uses that comforter. So, no new comforter until this person “kicks the head lice,” which means the lice is gone from his head. Many people who are sick and have a cold will often talk about trying to “kick this cold I have,” which means to get over it and start feeling better. You’ll also hear people talk about trying to kick a habit, like smoking. “I know smoking is bad for me. I’m trying to kick this awful habit.” Hope this helps!