let oneself in for

let (someone or oneself) in for

To involve someone or oneself in something, especially that which proves to be more intimidating, demanding, or overwhelming than one was expecting. I hope you know what you're letting yourself in for with this case—it's going to drag your reputation through the mud for a while. Just what have you let me in for, Tom? I said I wanted to earn a little bit more money, not get involved with the Mafia!
See also: let

let oneself in for something

to make oneself vulnerable to some difficulty. I don't want to let myself in for a lot of extra work. You really let yourself in for some problems!
See also: let