If u kiss a girl on the cheek AIDS can't be transmitted. But if it's a French kiss, then there is a risk that maybe u have a tiny cut on the inside of your mouth if even a tiny bit of blood is transferred from her to you, then u can get AIDS. The key thing to remember is that it transmits via body fluids (blood, semen, etc.). AIDS via oral sex is not as prevalent as via vaginal or anal routes, but there are cases where it has been transmitted.