My 7 month old chihuahua Kira humps my arm

my little chihuahua is becoming a woman.. This is the first time shes done it and hasnt done it since. I didnt even know female dogs did this. I know i should have corrected her but it was the first time and I was laughing too hard to do anything about it.
I just noticed how appropriate the audio in the background is for the video..its about a guy getting raped by a woman on Law and Order SVU