What does this weird comment mean?

Question

My 14-year-old sister said to me the other day, "I've got your heart in a headlock."

Answer 1

It could mean that she has got you exactly where she wants you.  For example if she told you a secret she knows that you wont tell becasue she knows you inside out.

Answer 2

I'm pretty sure a headlock is a wrestling position. I'm confused as to why she said it to you, as I'm sure to have someone's heart in a headlock is when someone is hopelessly in love with you and hanging off your every word.

So I'm thinking she used this term incorrectly.

Maybe you could ask her.