Who is being immature here?

Just tonight, my girlfriend farts in my face, which she finds pretty damn funny. I try to tell her she is disrespecting me and my personal space and she feels it is payback for me not getting the right cottage cheese earlier this day. Last night she farted bare on both sides of my pillow, she found that to be hysterical. At one point this evening I was trying to talk to my mother and she found it extremely amusing to be messing with my junk, I asked her to stop and she tells me no and seems to find it funny once again. I know her personality includes playing pranks, but they just seem immature and childish. Then when I retaliate or call her out she acts all offended like I can't take a joke. I don't know what to do to get through to her without her feeling like I'm controlling her, as she sometimes feels I do to her.