It's getting a goddamn zit at that point between your shoulderblades where you can only reach it by contorting like a graduate of the St. Vitus's School of Topless Dance.
There is a level of intimacy required to get a partner to deal with your rogue zits for you. This is not a casual relationship thing. This is not a friend thing. You have to committed. It is the level beyond being willing to fart in one another's presence. (It is slightly below the "Great, you've broken both arms and now need help on the toilet" level, mind you.)