give (one's) right arm
A figurative phrase that highlights one's interest in having something or eagerness to do something. A: "I'm going to the concert on Saturday!" B: "Aw man, I would give my right arm to have tickets to that!" I would give my right arm for your sister's gorgeous hair!
give your right arm
If you say that you would give your right arm for something or to do something, you mean that you want it very much. There are not many jobs I would give my right arm for. I can do nothing but think about my ex-husband. I would give my right arm to be able to start again. Note: Most people are right-handed, and so consider their right arm to be more important than their left.