I have this weird habit, but I don't think its so weird anymore.....?

I have this habit of popping bumps (pimples, blackhead etc.) on my husbands back, and for a long time I thought I was the only one. It wasn't until I started seeing this same behavior written into movies and tv shows that I realized its more than a personal thing. I also noticed that its always the wives who engage in the "poppin". My husband has no interest in poppin whatsoever. It's come to the point where I don't even have to look, I just feel my way around with my fingertips, then I pounce.... Where does this urge to pop come from, can anyone out there relate?