Why does my bf do this?

I can't stand it when people breath on the back of my neck! I giggle and squirm like crazy. My bf knows this, but sometimes he holds me down and breaths on my neck purposely while I'm trying to get away, giggling my head off. Why does he do it? Just because its funny how I squirm? Or is there an underline meaning here...like he likes to be in control or something...or...idk. Haha just curious. Thanks