What does (knock yourself out) mean?
"Knock yourself out" means to make a great effort, but usually for something fun. "She knocked herself out planning this party!" Sometimes it is used sarcastically, for example, if you are having trouble solving a homework problem, and a friend tells you that they could solve it easily. You would hand your paper over to them and say, "Here, knock yourself out." You're being sarcastic and implying that they will have fun solving what is to you a very tedious and difficult problem.