"some nerve" is used to describe people that have a lot of balls, guts, or nuts to ask or do something. It usually is used in a negative light.
For example: A homeless house guest that has been given a lot of gifts, a truck, a house of their own, and a job has "some nerve" to ask for more.
Homeless House guest: Thanks for the truck, house, job, and new clothes.
Hostess: Your welcome, I'm glad I could assist.
Homeless House guest: Before I move out into that new house with the new car you gave me, what happened to the birthday gifts you were going to give me?
Hostess: You have some nerve asking for more things when it's clear I have given you a lot.