Depends on what state you are in and whether you are an adult or a juvenile. In my state, smoking weed is not a state crime and so unless you get caught be federal DEA agents, that will not result in a crime.
"Sneaking out" probably has a meaning to you, but I do not know if your conduct amounts to trespass or some other crime.
If you are an adult and you assist a child in disobeying her parents, and you are in my state, then the charge is contributing to the delinquency of a minor. The maximum a court can impose is 6 months in jail. The usual is just a few days in jail, plus a restraining order. A second violation gets you a real sentence.