I have a 6 month boxer/coon hound female. She pee's outside, follows the command to "go potty" and the like. She is fixed and has had her shots. She never really stopped peeing in the house. Recently she has peed on my boyfriends leg, on our bed as well as on the carpet. Today I was playing with her, throwing her ball and she peed right next to me. Why does she do this, and what do I need to do to stop this behavior?

This really sounds like a veterinary problem, not behavioral. Her urination seems to be beyond her control. I recommend you take her to the vet. Since she's been neutered and has had all her shots, it's unlikely that she's marking territory (females don't often do this anyway), and she probably doesn't have a disease, but she might have issues with her bladder or urinary tract that can be remedied.