Well technically I am a girl, but I couldn't tell you how many times I've been slapped across the face by one of my female peers. And for some reason I'm always the one who gets introuble.
I remember the first time though. In fifth grade, I was walking down the hallway to the library, minding my own business. All of a sudden, a fourth grader twice the size of me and a least half a foot taller walks up to me. She asked me some questions, I answered, she said thank you, and then just freaking slapped me for no reason at all. Then she slapped me again, punched me in the stomach, pulled one of my braids, kicked my leg and pushed me. So she's wailing on me, and I finally start to try and defend myself by blocking one of her punches. She started screaming like I just stabbed her and ran crying to the teacher.
She got a popsicle, hugs from a sympathetic class and didn't have to do her homework for two days. I got detention for 2 weeks and my teacher hated me even more. She made me write "I will not beat up another student" at least 200 times.
I slapped my best friend once. I kinda feel bad about it now. He kept annoying me for some reason. He did all the stuff he KNOWS I find annoying in 5 minutes; basically chewing loudly, being touchy feely and other crap. Then when he picked up my DS, turned it off (therefore deleteing a lot of unsaved material) and pocketed it, I finally just slapped him across the face.