My daughter's bedroom door opens OUT and doesn't have a lock on the inside. We're trying to think of ways we can lock it because her dad just barges in after a knock. The door frame is too thick for a latch...any ideas?

Dad is in no way, shape, or form going to change. My daughter is trans and he doesn't recognize that. There are definitely deeper issues here but for the time-being I'm just looking for a way so that my daughter feels secure in her space.